
Book 



T~? 3 



COBBHGHT DEPOSIT. 



The 
CONTROL OF QUALITY 

In 
MANUFACTURING 



By 

B 

■ 



G. S. RADFORD 



Consulting Engineer; Member, American Society of 
Mechanical Engineers; Society of Naval Architects and 
Marine Engineers; American Society of Naval Engineers 




NEW YORK 

THE RONALD PRESS COMPANY 

1922 






Copyright, 1922, by 
The Ronald Press Company 



All Rights Reserved 



OCT 11*22 



>GI.A6S3637 



o. 



To My Parents 



PREFACE 

There is an erroneous but wide-spread belief that quality 
and high cost go hand in hand. The existence of this 
feeling is readily explained, because it is the general prac- 
tice to advertise quality as something worth paying for. 
From the purchaser's standpoint this is very true, but it 
does not follow by any means that quality is costly to pro- 
duce. Very high-grade "quality" products are often high 
priced, but lower grade and less expensive articles also 
possess their own quality standards. 

In the factory, quality is a costly thing to neglect, yet it 
is the usual experience to find a disproportionate emphasis 
being placed upon quantity of output, in the effort to effect 
economies. Often this is not so much due to lack of proper 
intent as it is to the failure to realize what the quality ap- 
proach means. To establish and maintain definite and 
sensible standards of quality requires care and thorough- 
ness. These are the very things which remove obstacles 
to production and thus decrease costs — quite independently 
of whether the product is high grade or low grade, high 
priced or low priced. 

In the following pages, presenting the results of an inten- 
sive study of quality in manufacturing, it has been the 
intention to show that the control of quality is the correct 
starting point for economy (as well as to obtain higher 
standards for their own sake), since if quality is under 
positive and continuous control, increase of output follows 
as a by-product advantage. Hence one of the central 
thoughts of the book is that increased output and decreased 
costs are more certainly attained when manufacturing 



vi PREFACE 

problems are approached with quality, instead of quan- 
tity, as the primary guide and objective. 

It is well-nigh impossible to pass a store window, or to 
ride in a street car, or to glance at the pages of a magazine 
without encountering the word "quality." Yet there is 
no formal literature about quality in manufacturing — 
nearly all of our attention having been devoted to quantity. 
Therefore, in constructing this book the introductory 
chapters, I and II, discuss the general relationships of 
quality to manufacturing. 

When it comes to controlling quality, inspection plays 
a large part. Chapters III to XI, accordingly, are intended 
to insure a clear understanding of the various forms of 
inspection. In sketching the relationship of inspection to 
the control of the flow of work in process, the idea of plan- 
ning with material in physical form is advanced as an 
advantageous extension of the usual planning systems. 

With this earlier portion of the book as a foundation, 
Chapter XII, et seq., takes up definitely the relation of 
measurement to quality and the development of quality 
standards in the various types of manufacturing, using the 
methods for controlling dimensional quality as the principal 
example. Dimensional work has been reduced to very pre- 
cise regulation in the industrial arts and thus permits of 
exhaustive treatment. Hence most of the illustrations 
throughout the book are drawn from that source as best 
typifying the principles involved in quality control generally. 

Among the important characteristics of manufactured 
articles there are many other qualities which as yet have 
not been brought to the same perfection of control as dimen- 
sion. Color, the control of which is just now beginning to 
receive close attention in many industries, is discussed as 
typical of these other qualities. 

The concluding chapters present the author's idea of the 



PREFACE vii 

best method of attack for approaching, and bringing under 
control, any quality problem whatever, regardless of the 
particular industry or the particular product which may 
happen to be involved. 

Throughout the text a careful effort has been made to 
give credit to the many firms and individuals who have 
supplied technical information and illustrative matter. 
Probably this book would not have been written if Mr. L. P. 
Alford, Editor of Management Engineering, had not re- 
quested me to do so, and then assisted in its preparation 
with his usual thoughtful and competent advice. It only 
remains to be said that doubtless many of the conclusions 
presented in the subject matter were influenced by profes- 
sional conversations with several former associates. It is a 
pleasant duty in this connection, to express my obligation 
especially to Messrs. William B. Ferguson, H. H. Pinney, 
D. C. Seagrave, Brigadier-General John T. Thompson, 
U. S. A., retired, and Captain R. M. Watt (C. C.) U. S. N., 
formerly Chief Constructor and Chief of the Bureau of 
Construction and Repair. 

G. S. Radford 
New York City, 
September I, 1922 



CONTENTS 



Chapter Page 

I Introduction 3 

The Changed Industrial Demand 

Quality a Distinguishing Characteristic of Goods 

Uniformity the Essence of Quality 

Standardization Does Not Bring Quality _ 

Uniformity Requires Continuous and Positive Control 

Instances of Failure in Quality Control 

Advantages of Considering Quality at Outset 

Improved Labor Relationships 

Testimony 

Increase of Output and Decrease of Costs 

Carnegie's Maxim 

Experience of War Time Manufacturing 

Control of Quality Basic 

The Quality Bonus 

Experience of The Shelton Looms 

Experience of the Armstrong Cork Company 

Decreased Selling Costs with Quality Goods 

II The Approach to Quality Control 25 

The Starting Point — Determining Nature of Product 

The Commercial Factors— Requirements of the Consumer 

The Design — Securing Consumer's Requirements 

Provision for Improving Design 

Materials 

Processes 

Workmanship 

Operating Organization and Records 

Inspection an Essential 

III Inspection — The Need for Independent Scrutiny 35 

Maintaining Standards — Measurement and Control 

The Instrument for Measuring and Controlling 

Convincing the Management 

Growing Importance of Inspection 

Inspection Often a Necessity, Always an Economy 

Need of Intensive Study of Inspection 

Study of Theory Needed 

Functions and Limits of Inspection 

IV The Types of Inspection 4 6 

Conformity with Special Factory Situation 
Material Inspection 
Office Inspection 
Tool Inspection 



x CONTENTS 

Chapter Page 

IV The Types of Inspection — Continued 

Process Inspection 

Advantages of Centralized Inspection 

Inspection Combined with Remedy of Defects 

Use of Special Mechanical Devices 

The Amount or Quantity of Inspection 

The Danger of Becoming "Fussy" 

Unnecessary Inspection 

The Percentage of Inspection 

Sampling — The Theory 

Safeguards for Sampling 

Other Economies in Inspection 

V The Inspection Department in the Organization. . 63 

Vital Importance of Inspection 

The Engineering Department 

The Production Department 

The Inspection Department 

A Parallel with Governmental Organization 

Inspection's Relation to Engineering and Production 

Purpose Help — Not Mere Criticism 

The Real versus the Apparent Organization 

Engineering and Inspection 

Production and Inspection 

VI Inspection's Contribution to General Service ... 74 

The Collection of Useful Information 

Trouble Reports 

The Inspector's Sense of Responsibility 

A Typical Instance 

Reception of Trouble Reports 

Inspection and the Assembling Department 

Benefits to Entire Factory 

An Example of Selective Assembly 

The Custody of Work in Process 

Stimulus to Order and Cleanliness 

The Analysis of Work in Process — "Good" and "Bad" 

Handling Rejected Parts 

Quality as an Incentive to Production 

The Individual Worker's Interest 

Interest in the Work Itself 

Expert Knowledge — Causes and Results 

Interest in Quality versus Fatigue 

A Phase of a Major Problem 

VII Inspection's Relation to Planning 95 

The Flow of Work in Process 
Uneven Flow — Disadvantages 
Effects on Piece Work 
Supply of Raw Materials 
Material in Process 



CONTENTS xi 

Chapter Page 

VII Inspection's Relation to Planning — Continued 

Insuring a Continuous Flow 

Planning with the Material Itself 

Master Planning 

The Operation Mark or Symbol 

Operation Mark to Remain Unchanged 

The Operation Data Sheet 

Route Tags 

The Manufacturing Schedule 

Allowance for Losses in Process 

Determining Quantities of Work in Flow 

The Design of Space Assignments for Planning with Material 

Inspection and Dispatching 

VIII Central Inspection 115 

The Most Advanced Form of Inspection 

Not Restricted to One Form 

Value of Self-Counting Trays 

The Two-Bin System Extended 

Systematic Layout for Material in Process 

Layout of Central Inspection Crib 

Construction of Central Inspection Cribs 

An Adaptation to Rough Work 

The Resulting House Cleaning 

An Adaptation to Close Work in Metal 

Aisle Arrangement 

Advantages of Several Centralized Inspection Spaces 

Standard Arrangement Desirable 

Summary of Advantages 

IX The Organization of the Inspection Department 139 

Designing the Instrument for Controlling Quality 

The Development of Organization 

The Chief Inspector 

Duties of the Inspection Department 

Work Related to Process Inspection 

The Line Organization 

Special Value of Understudies 

Duties of Inspectors 

The Chief Inspector's Staff 

The Inspection Department Personnel 

The Bench Inspector 

The Floor-Inspector 

Salvaging Native Ability 

A Case in Point 

Study the Individual 

X Management of the Inspection Department .... 156 

The Task 

Co-ordination 

The Use of Conferences 



xii CONTENTS 

Chapter Page 

X Management of the Inspection Department — Continued 

Letters of Instructions and Advice 

Reduction of Turnover of Inspection Force 

Provision for Promotion 

Wages 

Piece Work in Inspection 

Working Hours 

The Cost of Inspection 

Teaching Inspectors 

Combine Instructions with Staff Supervision 

Unskilled Help in Inspection 

Female Labor for Inspection Work 

Women Inspectors on Heavy Work 

Morale 

XI Inspection in Practice 172 

Type Varies with Individual Factory 

When to Use Extensive Inspection 

Inspection in Automobile Plants 

The Packard Inspection Service 

An Example of Former Practice 

Machine Tool Industry 

Small Precision Work 

General Machine Shop and Foundry Practice 

Special Cases 

Ratio of Inspectors to Workers 

XII Quality Control in Practice 187 

Complexity of the Problem of Quality 

The Shell Contracts of the American Locomotive Company 

Beginning the Work 

No Rejections After Delivery 

Shells 

Bullets 

Time Fuses 

Quality First — Then Quantity Follows 

Liberty Motors at the Lincoln Motor Company 

Remington Arms Company — Springfield-Enfield Rifle Production 

Quality Is the Road to Production 

XIII Measurement and Errors 210 

The Evolution of Measuring 

The Selection of Characteristic Qualities for Measurement 

Standard Samples 

Dangers of Standard Samples 

Measurement by Comparison with a Standard Scale 

The Measuring Instrument 

Danger of Overgraduation 

The Need of a Final Check 

The Choice of Instruments 

The Precision of Measurement 

Precision of Workmanship 



CONTENTS xiii 

Chapter Page 

XIII Measurement and Errors — Continued 

The Theory of Errors 

When Theory and Practice Differ 

The Chain of Inaccuracy 

The Chain of Wear 

The Cure for Errors 

XIV Quality Defined — The Ideal Standard 233 

Characteristic Qualities of Product Must Be Known 

Quality Varies Continually 

Development of the Design 

The Theoretical Standard 

The Ideal Standard 

Progress Toward More Exact Designs 

Changes in Design Must Be Avoided 

When Improvement Changes Should Be Alade 

Every Cause Has Several Effects 

Precautions to Avoid Changes 

XV The Working Standards 264 

The Compromise in Setting Tolerances 

Raw Material Standards 

Conditioning Standards 

Standards of Finish 

Standards of Dimension and Form 

Allowed Variations Defined 

Necessary Precautions 

Dimensional Working Standards 

Assembling Standards 

Final Tests 

Recapitulation 

XVI Repetition Manufacturing 264 

Uniformity for Economy 

Uniformity of Product Means Uniformity Throughout Production 

Interchangeable Manufacturing 

The Industrial Revolution 

The Mechanical Revolution 

Economy in Assembling 

The Work of Simeon North and Eli Whitney 

Continuous Standardized Production 

Vital Importance of Uniform Quality in Raw Materials 

Continuous Processing 

Duplicate Manufacturing 

Partial Interchangeability 

Production of Machine Tools 

The General Prniciple 

XVII The Dimensional Control Laboratory 281 

Practical Value of Precision 
The Laboratory Proper 



xiv CONTENTS 

Chapter Page 

XVII The Dimensional Control Laboratory — Continued 

The Surface Plate 

The Dimensional "Court of Highest Appeal" 

The Brown and Sharpe Measuring Machine 

The Pratt and Whitney Standard Measuring Machine 

The Johansson or Swedish Block Gages 

The Pratt and Whitney Precision Gages 

Comparators 

Miscellaneous Equipment 

Personnel 

XVIII Gages and Gage-Checking . 303 

When Should Fixed Dimension Gages Be Used? 

Fixed-Dimension Limit Gages 

Adjustable Limit Gages 

Multiplying Gages 

Special Gages 

Gage Tolerances 

The Application of Gages 

Gage-Checking 

The Slip in Transferring Size 

XIX Thread-Gaging 317 

Evolution of Thread-Gaging 

Inter-relation of Thread Elements 

Working Thread Gages 

The Hartness Comparator 

Other Equipment for Measuring Threads 

Thread Gage Tolerances 

Precision Depends upon Service Requirements 

XX The Precise Control of Processes 330 

What Dimensional Precision Is Practicable? 

Automobile Experience 

Tables of Tolerances 

Precautions for Obtaining Precise Work 

The Principle of Balance 

The Effect of Finish on Accuracy 

Quick Checks on Precision 

XXI The Control of Color 346 

Application of Measurement to Other Qualities 

Appearance and Color 

Standard Samples 

The Standard Color Card 

Dangers of Standard Samples 

What Is Color? 

The Illuminant 

The Subject 

The Eye 

The Color Constants 



CONTENTS xv 

Chapter Page 

XXI The Control of Color — Continued 

Color Vision 

Methods of Analyzing Color 

Analysis By Primary Colors 

Instruments for Measuring Color 

The Spectrophotometer 

The Monochromatic Colorimeter 

Auxiliary Instruments 

Reduction of Errors in Color Work 

Standards of Appearance 

XXII The Scientific Attitude of Mind and Its Methods 368 

Science and the Arts 

Science and the Practical Man 

Theory or Theorists 

The Engineer as Co-ordinator 

The Scientific Attitude 

The Scientific Method 

The Place of the Engineer 

XXI 1 1 The Method of Attack to Control Quality .... 377 

The Approach to the Problem 

Uniformity within Limits 

Getting the Facts 

Analysis 

Tripartition or Tripartite Analysis 

Quality Records 

Using the Facts — Synthesis and Adjustment 

The Order of Procedure 

Begin with the Product 

Written Descriptions of Processes 

The Assemblage of Processes 

Organization and System 

Conclusion 



LIST OF ILLUSTRATIONS 



Figure Page 

i. Full Set of Johansson Gage Blocks n 

2. Time Fuse Manufacture of the American Locomotive Company . . 18 

3. An Object Lesson in Quality 22 

• 4. A Common Method of Holding a Micrometer Caliper 28 

5. Measuring a Turned Piece in Lathe 31 

6. A Centralized Inspection Point in the Lincoln Motor Company's 

Plant 37 

7. Tool and Gage Inspection at the Packard Motor Car Company's 

Factory 42 

8. Some of the Special Equipment of the Tool and Gage-Checking 

Room — Lincoln Motor Company 48 

9- Inspection of 9.2-Inch Shells — American Locomotive Company . . 51 

10. Rough Stock Inspection — Packard Motor Car Company 58 

11. Sample Checking Room — -Packard Motor Car Company 65 

12. Inspection Room — -Lincoln Motor Company 71 

13. Trouble Report 76 

14. Inspection Form — American International Corporation, Hog Island 80 

15. Gear Inspection — Lincoln Motor Company 88 

16. The Flow of Work in Process — Shell Work of American Locomotive 

Company 96 

17. Operation Study Sheet as Used at the Bridgeport Armory of the 

Remington Arms Company 105 

18. Operation Data Sheet 106,107 

19- Route Tag — Remington Arms Company 108 

20. From Forging to Finished Crank-Shaft 118 

21. A Wood Frame Truck 119 

22. An "A" Frame Wood Truck for Connecting Rods 120 

23. Standard Steel Tote Boxes 121 

24. Diagram of Line of Flow of Work 123 

25. Diagrammatic Shop Arrangement 124 

26. Diagram of Relative Size of Space Assignments 125 

27. Transporting Rack for Rifles — Remington Armory, Bridgeport . . 126 

28. Type Section of Central Inspection Crib 127 

29. Floor Plan of Central Inspection Crib 128 

30. Floor Plan of Canvas Shop 129 

31. Typical Modern Shop Floor Plan 132 

3 2 - Modern Shop Floor Arranged for Central Inspection 133 

33. Type Floor Plan of Central Inspection Crib 135 

34. Type Arrangement of Material Storage Point in Central Inspection 

Crib 137 

35. Organization Chart — Inspection Department 145 

36. Various Sorts of Special Manufacturing Gages 150 

37. Curve of Output and Number of Men 163 

38. Prestwich Fluid Gage as Used to Inspect Piston Pins 167 

39. Inspection Organization Chart — -Packard Motor Car Company . . 174 

40. Inspector's Tag Disposing of Work — Packard Motor Car Company . 1 76 

41. Piston Ring Inspection— Packard Motor Car Company 179 

42. Inspection of Time Fuse Parts 183 

43. Perch for Inspecting Textile Fabrics — The Shelton Looms .... 185 

44. Typical Pages from Shop Instruction Book 192-196 

xvi 



LIST OF ILLUSTRATIONS xvii 

Figure Page 

45. Work Table Layout and Operation List for Time Fuses 198 

46. Fuse Body Inspection Layout 199 

47. Special Gages for Bottom Rings of Time Fuses 202 

48. Typical Operation Sheet — Lincoln Motor Company 204 

49. Typical Instructions for Inspection — Lincoln Motor Company . . . 205 

50. Standards of Weight and Length for the United States 216 

51. Method of Using Hub Micrometer Caliper No. 241 — Brown and 

Sharpe Manufacturing Company 218 

52. Setting a Johansson Adjustable Limit Snap Gage by Means of 

Johansson Gage Blocks 222 

53. Probability Curve, Showing the Frequency of Occurrence of an Error 228 

54. Checking Johansson Adjustable Limit Plug Gage with Gage Blocks 

Mounted in Holder 235 

55. Use of Johansson Gage Blocks and Sine Bar to Check Taper of a 

Milling Cutter Shank 239 

56. Set-Up of Johansson Blocks for Checking Taper of a Special Plug 

Gage 241 

57. Order for Change in Drawing 246 

58. Measuring Diameter of Automobile Piston 253 

59. Reading Inside Micrometers After Measuring Inside of Cylinder . 257 

60. Measuring Large Diameter of Piece in Grinder 260 

61. Height Gage Used with Johansson Blocks 268 

62. Set-Up of Johansson Blocks to Check Drill Jig 273 

63. Special Milling Fixture Using Johansson Gage Blocks for Locating 

Purposes 276 

64. An Excellent Dimensional Control Center 282 

65. Brown and Sharpe Measuring Machine 288 

66. Pratt and Whitney Measuring Machine 290 

67. Details of Measuring Head — Pratt and Whitney Measuring Machine 292 

68. Special Set of Johansson Block Gages 297 

69. American Amplifying Gage Used With Swedish Gage Blocks . . . 299 

70. Group of Brown and Sharpe Gages 305 

71. Adjustable Limit Snap Gages — Pratt and Whitney Type 307 

72. Adjustable Limit Plug Gages with Reversible Ends — Pratt and 

Whitney Type 308 

73. Pratt and Whitney Taper Gages 315 

74. An Exaggerated Form of Stud 320 

75. Typical Thread Gages — Pratt and Whitney Company 322 

76. Typical Thread Gage — Pratt and Whitney Company 323 

77. General View of Hartness Screw Thread Comparator 324 

78. Another General View of Hartness Screw Thread Comparator . . . 324 

79. The Work Holder and Projection Lens of Hartness Screw Thread 

Comparator 325 

80. Sketch of Drill Showing Various Fits — Johansson 334 

81. Diagram of Limit System — Shaft Basis — Johansson 335 

82. Tolerance System (Table) with the Shaft as Basis — Johansson . . . 336 

83. Diagram of Limit System — Hole Basis — Johansson 337 

84. Tolerance System (Table) with the Hole as Basis — Johansson . . . 338 

85. Chart for Spectral Analysis of Color Showing Relative Visibility 

Curve 352 

86. Chart for Spectral Analysis of Color Showing Typical Color Analyses 

Plotted as Curves 357 

87. Sketch of Prism and Spectrum 359 

88. Diagram of Spectrophotometer 363 

89. Precision Torsion Balance — Roller-Smith 386 



The Control of Quality 
in Manufacturing 



CHAPTER I 
INTRODUCTION 

The Changed Industrial Demand 

The years 1919 and 1920 marked definitely the end of a 
period in manufacturing and industry. It was characterized 
by the demand for "maximum production," for quantity or 
volume of manufactured goods. The means and agencies 
of production — material, equipment, and labor — were 
planned and directed to satisfy this end. But with the 
close of this period has come a great change which will 
vitally affect industry and manufacturing of the present 
and immediate future. 

The new demand is for effective unit production, that is, 
a maximum useful and marketable output per machine, per 
hour, per man. "Useful, marketable" production implies a 
different characteristic from that associated with mere 
quantity. This characteristic is quality. It is destined to 
distinguish the great purpose in present and future manu- 
facturing, in the same way that quantity demand distin- 
guishes the period which has closed. 

At the outset it must be recognized that both quantity 
and quality are general or "universal" characteristics in 
that they apply to all manufactured goods. The horizon of 
quality is just as broad as the horizon of quantity. This is 
their similarity — they both belong to all kinds of goods and 
articles. Quality belongs to those articles which are in- 
expensive no less than to those which are costly. It is 
closely associated with usefulness and marketable possibili- 
ties. It is a characteristic emphasized again and again in 
advertising and sales literature, but has no direct connection 

3 



4 THE CONTROL OF QUALITY 

with cost or selling price. A point to note is that whether 
the article costs much or little, quality and the reputation 
for quality establish the market which will make possible 
quantity production and its attendant advantages. 

Quality a Distinguishing Characteristic of Goods 

The term "quality," as applied to the products turned 
out by industry, means the characteristic or group or com- 
bination of characteristics which distinguishes one article 
from another, or the goods of one manufacturer from those 
of his competitors, or one grade of product from a certain 
factory from another grade turned out by the same factory. 
Quality serves to identify an article. It is the character- 
istic which measures the evenness of a specific grade. Qual- 
ity is used in this sense whenever we say that the same 
factory produces the same article in several different qual- 
ities, or that the output of certain factories is graded 
according to quality. 

It is evident that the group or combination of charac- 
teristics which form the quality of an article includes such 
elements as design, size, materials, workmanship, and finish. 

To consider some of these elements — so far as size is in- 
volved, quality is concerned with precise adherence to size. 
For instance, one pair of shoes of a specified length and 
width must be like another pair of shoes of the same length 
and width. In this case quality depends upon adherence to 
a particular characteristic. The same requirement holds in 
regard to the raw materials from which the article is made 
and to the workmanship applied in the manufacturing. A 
manufacturer to secure and maintain quality attains uni- 
formity or evenness in the raw materials which enter his 
product and in the workmanship applied. This adherence 
to established requirements is a major responsibility of the 
manufacturer. 



INTRODUCTION 5 

Uniformity the Essence of Quality 

The purchaser's principal interest in quality is that 
evenness or uniformity which results when the manufac- 
turer adheres to his established requirements. No matter 
when or where the purchaser buys an article he expects the 
same definite and proper return for his money, not only at 
the time of purchase but through a reasonable period of use. 
He is justified, no doubt, in expecting a gradual improve- 
ment from time to time in the quality of all the articles which 
he buys, but at any one time his chief expectation, as re- 
gards quality, is that it shall be the same for like articles. 
No shoe must be either better or worse than its mate. The 
quality of two pairs of the same grade of shoes, or of ten or a 
thousand pairs for that matter, must be practically identical. 

The manufacturer himself as a purchaser of raw ma- 
terials, supplies, and equipment, views the matter in the 
same light, perhaps with even greater insistence upon uni- 
formity and evenness of grade. Thus he requires that all 
lots of a given kind of steel shall have the same characteris- 
tics from lot to lot; and, as just indicated, the evenness of 
characteristics and the degree of precision with which they 
are attained are what determines quality. As a matter of 
fact, the manufacturer is often more concerned with obtain- 
ing uniformity in raw material than he is in getting an im- 
proved quality, because it is easier to produce uniform 
results from material which is uniform to begin with, and 
uniformity of product is what he is after. 

Standardization Does Not Bring Quality 

At this point it is important to realize that standardiza- 
tion of products or articles does not of itself influence 
quality. Unfortunately, these two terms are frequently 
confused in use, but they are not synonyms. One signifies a 
characteristic, the other a process. 



6 THE CONTROL OF QUALITY 

Standardization in American industry has been applied 
in general to the proportions of articles and is frequently 
referred to as " standardization of proportionality. ' ' An ex- 
cellent example is the United States standard screw thread. 
This was adopted many years ago and is generally used 
throughout American industry. However, it is. possible to 
make United States standard threads of poor quality, good 
quality, or of any intermediate quality. If the proportions 
are the same throughout this range of quality, all of the 
screws would be "U. S. S." Another example, appreciated 
by everyone, is presented by our railroads. A standard rail- 
road gage is almost universally used throughout the United 
States, yet everyone has discovered that there is no stand- 
ard in the quality of these standard-gage roadbeds. That 
is, while the gage is standard, the quality of the roadbeds 
varies. The distance between the rails is only one of a 
number of elements which make up the quality of the road- 
bed itself. So far as the gage is concerned, the requirement 
of quality is attained when the rails are maintained at the 
standard distance apart. But the smoothness of the road- 
bed depends upon many other things, which grouped to- 
gether give characteristics or quality. 

The quality of an article, therefore, is made up of a large 
number of characteristics or attributes, some of which may 
be standardized for convenience or economy. It is quite 
possible to have two articles, both standard, which appear 
alike, but whose quality differs essentially. In the case of 
raw materials, ordinary city water undoubtedly is handled 
in greater bulk than any other standard commodity. When 
collection and filtration are completed, the water is said to 
be distributed in standard form ; but even then its quality 
differs widely from place to place and from time to time. 
Although alike to all outward appearances, the water supply 
in two cities may be far different in essential quality, be- 



INTRODUCTION 7 

cause the ingredients which cause a quality difference are 
usually incapable of detection by human senses. In this 
instance also, quality depends on the consumers' require- 
ments. Thus water may be satisfactory for cooking but 
not at all satisfactory for many industrial and technical 
purposes. . 

In the case of manufactured articles the same difference 
must be recognized between standards and quality. Re- 
ferring again to shoes as an example, the purchasing public 
requires footwear in a great variety of sizes and kinds, and 
exact satisfaction of each individual's wants would result in 
almost as many kinds of shoes as there are persons. To 
avoid making such an indefinite number of varieties and 
sizes it is necessary to standardize some of the elements 
through striking a compromise. The effect of this process 
is to create a sufficient volume of like work to permit of using 
the method of quantity production. This compromise for 
the purpose of securing the economy of repetition manu- 
facturing takes place when shoes are classified in a stand- 
ardized series of styles, sizes, and widths. A little reflection 
will show that this process of compromise or standardiza- 
tion is quite different from the establishing of quality or 
qualities which define the character of any particular make 
and grade of shoe regardless of size and of style. 

Uniformity Requires Continuous and Positive Control 

In meeting and satisfying the purchaser's expectations, 
the manufacturer's problem would be very simple indeed if 
quality were some definite thing which could be easily and 
accurately measured out so much to an article — but it is 
not. On the contrary, quality tends to slip away, to change 
and, in fact, be almost everything except what it should be. 
The perversity of inanimate things and the fallibility of 
animate persons are always at work to render quality fugi- 



8 THE CONTROL OF QUALITY 

tive. In this respect quality differs markedly from quan- 
tity. It is comparatively easy to say that we will make a 
thousand articles and to proceed to make them. The prob- 
lem becomes difficult only when we are required to make 
them alike within precise commercial limits and with mini- 
mum variations from standard. 

This difficulty in attaining uniform standards of quality 
in manufacturing makes the control of quality so vitally 
important. The advertised claim of quality is one thing but 
the positive and continuous control of quality to definite 
standards in the factory is something altogether different — ■ 
as many people have discovered in recent years. By ' ' posi- 
tive control of quality" is meant that form of manage- 
ment or direction which establishes the quality requirements 
and then sets up the organization and selects the personnel 
capable of securing that quality. By "continuous control 
of quality " is meant the vigilant maintenance and direction 
of the organization and personnel set-up to make the control 
positive. 

The resulting and final quality of a manufactured article 
is created and influenced by a great number of things. In 
fact each element of the business plays some part in the 
final result. Consequently the control of quality must be 
positive in action in order that all the factors and agencies 
involved may be co-ordinated. If one factor gets out of 
control, the entire system is thrown out of adjustment, errors 
accumulate, and quality suffers. 

The control must be continuous because quality is not 
one of those things which once established stays put for all 
time. Its tendency to slip away is incessant. But a single 
serious slip in quality may result, in some businesses — for 
example in the manufacture of foodstuffs — in the destruc- 
tion overnight of a good-will which has required years to 
build up. 



INTRODUCTION 9 

Instance of Failure in Quality Control 

In most successful and long-established industries it has 
become a fixed habit to consider quality as basically neces- 
sary and thus to take it for granted. Most of these people 
sincerely believe that they have quality under control, and 
that once having attained a certain standard nothing more 
is necessary to perpetuate it indefinitely. Not long ago an 
engineer happened to spy a small sewing machine in the 
window of a Fifth Avenue store. It was of a standard make 
and therefore presumably of standard quality. It hap- 
pened that he had a place where such a machine might be 
used advantageously so he purchased one, which was handed 
to him in the original container. Upon trial, however, the 
machine proved to be very stiff and jerky in its action. So 
he personally took it back to the store and was informed 
that such a thing could not be. 

"Every one of our machines is inspected before it leaves 
the factory, but you may take it to Miss X at the repair 
desk in the rear. ' ' Miss X took one look at the machine and 
said, "Yes, the looper shaft is not straight. We get a good 
many that way. I'll give you another one." 

The second machine proved to be only a little better than 
the first. By this time the engineer was interested in the 
problem as an engineer, so he proceeded to take the ma- 
chine apart and discovered that the shaft had nothing to do 
with the trouble but that a slight filing and fitting of three 
other parts remedied the difficulty, so that his machine 
finally "ran like a sewing machine." He was especially in- 
terested to note, however — and this is the point of the story 
— that all of these difficulties should have been corrected 
and could easily have been corrected in the manufacturing 
of the parts, with a probable reduction in cost of assembly. 
This, it may be noted, is quite aside from the question of the 
reflection on this particular manufacturer's reputation for 



10 THE CONTROL OF QUALITY 

quality, for it is obvious that the engineer referred to is not 
going to buy a life-sized machine of that particular make 
until he has made sure that other manufacturers do not mar- 
ket a more uniformly satisfactory product. 

The experience just recited is significant of what happens 
with many concerns. The manufacturer in question has 
had a long-established reputation for a satisfactory product 
and it would be an extremely difficult and painful under- 
taking to make him believe that his control of quality had 
slipped badly in this instance. He probably believes that 
he has always had quality and consequently that he always 
will have it. He regards it as a part of his fixed assets. 

In order to get quality under proper control it is necessary 
to note that every phase of the business from designing to 
shipping is involved and requires critical examination. It 
is not merely a matter for the inspection department to take 
care of. For example, here is a factory which sets up a 
very high standard of dimensional accuracy on paper. The 
plans call for splitting thousandths of an inch in the manu- 
facturing processes. It has an elaborate and expensive 
inspection department, but it lacks the modern mechanical 
methods for checking the accuracy of its measuring instru- 
ments. It cannot possibly attain the dimensional precision 
called for by the plans, because of the failure to provide a 
comparatively inexpensive bit of apparatus. Yet the people 
in the factory think that they are doing remarkably fine 
work, while as a matter of fact they are only fooling them- 
selves. Their measuring instruments read to the precision 
required but they do not measure to that precision — which 
is something entirely different — and there is no positive way 
of checking them when they wear. In this instance, as a 
matter of interest, the management was not even aware of 
the fact that their dimensional checking arrangements were 
deficient and antiquated. 



INTRODUCTION 



II 



Here is another factory which is in nearly the same situa- 
tion but for a different reason. It has all of the apparatus 
and all of the provisions for inspection that are necessary, 
but the work in process is under such unsystematic regula- 
tion that the inspectors are frequently unable to tell you 
with certainty what parts have been rejected for minor 
defects and what parts are satisfactory and up to standard. 
Disorder in the shops has been carried over into the quality 
of the output. 

These are by no means isolated examples, nor are they 
exceptional cases. 



B^iip 


^ aar **" **^ 






_. m • m ■ 


^1 




\Z^^Sk 


■■ 



Figure I. Full Set of Johansson Gage Blocks 

Set No. i, consisting of 81 blocks; 300,000 different dimensions are possible with this set. 

There are other sets, but this is the one most used in America. Millimeter sets are also to be had. 

All blocks are accurate to within one-hundred-thousandth of an inch per inch of dimension. 



12 THE CONTROL OF QUALITY 

Advantages of Considering Quality at Outset 

The idea seems to prevail that, because quantity produc- 
tion has been desired, quantity itself is the proper starting 
point in attacking production problems. This idea is seem- 
ingly supported by the honest belief in many industries, 
both large and small, that everything which should be done 
in regard to quality is being done. As a result, quality con- 
trol has been disregarded and the demand for quantity has 
been kept in the forefront. 

Now the fact of the matter is that in concentrating di- 
rectly on quantity production and hence taking quality 
very much for granted or treating it as a secondary consid- 
eration, we have been overlooking an opportunity; and the 
oversight is costly in more ways than one. This is proved 
at once if we stop to consider the advantages which accrue 
from approaching management problems with quality in- 
stead of quantity as the primary criterion. There are 
immense and as yet largely undeveloped economies to be 
found when management is critically scrutinized from the 
quality standpoint. These resulting advantages are quite 
apart from the direct advantage of quality for its own sake, 
since they result in better labor relationships, increased out- 
put, and decreased costs. 

Improved Labor Relationships 

Let us consider the point of labor relationships. These 
present an ever and most pressing factory problem. The 
moment you endeavor to get an increase in output (which 
is attacking the problem from the standpoint of quantity) 
the question of bargaining enters and provides an occasion 
for dispute. On the other hand, if the workman is taught 
to better his product, and is urged to be more careful, and 
to be sure that his work is performed correctly, a common 
meeting ground is provided. It is a poor mechanic indeed 



INTRODUCTION 13 

who does not take sufficient interest in his work to join you 
in improving the results of his craftsmanship. 

Suppose now for the moment that this greater attention 
to quality, requiring thoroughness and attention to detail as 
it does, will result in an actual increase in output for the 
same effort. I say "suppose" that it does, although as a 
matter of fact it will be proved presently that there is no 
supposition about it. But assuming for the moment that 
more attention on the part of the workman to quality will 
bring about an increase in output, have we not secured that 
increase in a much pleasanter, more effective, and more 
permanent way than if we had made a direct request for in- 
creased production? It is in every way more satisfactory 
to discuss a factory problem on a basis in which both sides 
are mutually interested and moving in a common direction 
which brings them closer together. 

In order to carry out such quality discussions intelli- 
gently, the management must be informed, and very 
thoroughly informed at that, about the technical side of the 
business. Certainly this alone is a desirable thing. This 
method of approach is bound to lead into a study of the 
technical details of the business, to the mutual edification 
of both management and men. Failures to attain quality 
standards take the form of variations in the characteristic 
qualities. These errors in manufacturing must be listed 
and evaluated, and the basic causes of the errors located and 
cured, all of which is bound to be both stimulating and in- 
tensely interesting. It is about the only sure basis for off- 
setting the well-recognized danger of the modern industrial 
system. Men cease to be mere automatons when they 
think in this way about their work. 

It is a fact that the manager who strives to interest his 
organization in improving the quality of the work done will 
find that the process will work out to be a wonderfully effec- 



14 THE CONTROL OF QUALITY 

tive co-ordinator. When the men are trying for better and 
more careful workmanship, there is small chance of those 
disputes and arguments which so frequently arise when 
pressure is applied for more output. There is a world of 
difference between bargaining and appealing to the pride of 
craftsmanship. By the very reason of his being an artisan 
the worker is interested in improving his work. 

Testimony 

In 19 12, a report was submitted to the American Society 
of Mechanical Engineers on "The Present State of the Art 
of Industrial Management," which quoted an earlier paper 
by L. P. Alford and A. Hamilton Church on "The Princi- 
ples of Management," 1 setting forth the latter as: 

1. The systematic use of experience, 

2. The economic control of effort, and 

3. The promotion of personal effectiveness. 

Both of these papers dwelt upon "the conscious trans- 
ference of skill" (which necessitates that the management 
must first have the skill to transfer) as a vital step in pro- 
moting the personal effectiveness of the worker. There 
thus begins to appear an attitude toward management, 
which, when translated into general practice, is bound to 
have a profound influence on the labor situation. The 
evidence is strong that managers are leaning more and more 
towards this point of view, accentuated by a stronger and 
growing realization of the value of stressing quality. 

At the annual meeting of the American Society of Me- 
chanical Engineers in December of 191 9, Robert B. Wolf 
(then manager of the Spanish River Pulp and Paper Mills, 
Ltd., of Sault Ste. Marie, Ontario) presented a paper on 
"The Use of Non-Financial Incentives in Industry," which 
was recognized at once as containing many original and 

. American Machinist, May 30, 1912, Vol. XXXVI, p. 857. 



INTRODUCTION 1 5 

thought-provoking ideas that were widely discussed. The 
following is taken from Mr. Wolf's paper: 

Such records can be grouped under three main headings: quan- 
tity records, quality records and economy or cost records. Quality 
records which occupy the middle position, are, perhaps of the great- 
est importance, for they bring the individual's intelligence to bear 
upon the problem, and as a consequence, by removing the obstacles 
to uniformity of quality, remove at the same time the obstruction to 
increased output. The creative power of the human mind is, how- 
ever, not content simply to produce the best quality under existing 
conditions of plant operation. The desire to create new conditions 
for the more highly specialized working out of the natural laws of 
the process demands expression, and this expression at once takes 
the form of suggestions for improvements in mechanical devices. 

Only recently a paper was presented by W. N. Polakov 
entitled, "Making Work Fascinating as the First Step 
Toward Reduction of Waste." 2 This paper is carefully 
worked out and will repay reading with the general attitude 
of mind which recognizes the great desirability of organizing 
work "so that the worker's intelligence and his creative or 
imitative instincts will be brought into play. This requires : 
(i) analysis of jobs and processes to bring out the interrela- 
tion of causes and effects, and (2) the education of operators 
in conscious control of these forces and relations so that they 
can at will influence the results." This quotation is indic- 
ative of Mr. Polakov's attitude, but the reader is referred 
to the original text for a more thorough presentation of the 
subject. 

Increase of Output and Decrease of Costs 

Let us now consider the effect which the control of 
quality produces in increasing output and decreasing costs 
of manufacturing. The statement has already been made 
that such an increase in the volume of production does result 

-Mechanical Engineering, Nov. 1021. 



1 6 THE CONTROL OF QUALITY 

from the establishment of adequate quality control, and 
that it further results in a decrease in the cost of production 
as well. This idea was advanced in brief form in a paper 
by the author, published in October, 191 7. 3 Time and a 
subsequent study of a number of manufacturing enterprises 
have only served to strengthen these significant conclusions. 

Before exploring the basis of these conclusions, it is wise 
to remember that quality of itself is not a costly thing. For 
example, one buys a Ford car, not necessarily because it is 
cheap, but because it is built to a rather definite standard of 
quality and the purchaser has every reasonable assurance of 
obtaining a known return for his investment without refer- 
ence to price or time. Although the Ford car is compara- 
tively inexpensive, it has definite quality. 

The misapprehension that quality is costly doubtless 
arises from the fact that it is used as the chief inducement 
to make people spend money. In current use, moreover, 
the phrase "quality production" as distinguished from 
"quantity production" does not imply the idea of manu- 
facturing to certain predetermined standards of quality so 
much as it does that the quality of material and workman- 
ship is of unusually high grade. 

From this latter mode of thinking has arisen a wide- 
spread belief that quality is expensive and that it is always 
cheaper to make things to a lower standard. So it is, if we 
are working intentionally to a lower grade and definite 
standard ; but usually a lower grade article implies indefinite 
and inaccurate standards, poor material and slipshod work- 
manship, and little, if any, inspection. In such case the 
output^is lower and the work more expensive than if the 
thing were done correctly and well in the first place. It is 
axiomatic that it is always cheaper to make things right at 
the start. 



"The Control of Quality," by G. S. Radford, Engineering Magazine, Oct. 1017, 



INTRODUCTION 1 7 

Carnegie's Maxim 

One of our greatest manufacturers clearly understood 
that quality by itself is not necessarily costly, but it is always 
expensive to ignore; as the following quotation indicates. 
Almost everyone knows that the success of Andrew Carnegie 
was founded in meeting the ' ' impossible ' ' requirements of 
the United States Navy Department for a much higher 
grade of steel ; so it is interesting at this point to note what 
he has to say relative to quality in his "Autobiography" : 

We were as proud of our bridges as Carlyle was of the bridge his 
father built across the Annan, — "An honest brig" as the great son 
rightly said. 

This policy is the true secret of success. Uphill work it will be 
for a few years until your work is proven, but after that it is smooth 
sailing. Instead of objecting to inspectors, they should be wel- 
comed by all manufacturing" establishments. A high standard of 
excellence is easily maintained and men are educated in their effort 
to reach excellence. I have never known a concern to make a de- 
cided success that did not do good, honest work, and even in these 
days of the fiercest competition, when everything would seem to be 
a matter of price, there lies still at the root of great business success 
the very much more important factor of quality. The effect of at- k 
tention to quality, upon every man in the service, from the presi- 
dent of the concern down to the humblest laborer, cannot be j 
overestimated. And bearing on the same question, clean, fine work- y 
shops and tools, well kept yards and surroundings, are of much 
greater importance than is usually supposed. "Somebody appears 
to belong to these works" remarked one of a party who passed 
through the works. He put his finger there upon one of the secrets 
of success. 

The surest foundation of a manufacturing concern, is Quality. 
After that, and a long way after, comes Cost. 

Experience of War Time Manufacturing 

The analysis of enterprises which were intensified by 
war conditions illustrates the point vividly. It is now more 
generally realized that the specifications furnished for war 



THE CONTROL OF QUALITY 




INTRODUCTION 19 

material (unfortunately for the manufacturer) were inexact 
in many cases, so that great latitude existed for the applica- 
tion of judgment by inspectors, this being specially true in 
the case of the earlier contracts for foreign material. When 
the contractor failed to clear up all doubtful points affecting 
quality at the start, and plunged boldly into large-scale 
manufacturing, the resulting failure of the good old methods 
of quantity production came as a distinct shock to both 
engineers and manufacturers. 

The lessons to be drawn from these experiences are mani- 
fold, but close examination will reveal the fact that the 
manufacturers who were more careful in all matters deter- 
mining and affecting quality, reaped a greater harvest in the 
end, although they usually took longer to get started. The 
most clearly marked contrast between those who achieved 
results and those who did not do so well is to be found, in 
every case, in more exact definitions of quality backed up by 
an inspection service and general control of quality adequate 
for safeguarding the standards established. It is undoubt- 
edly true, moreover, that when the precautions just stated 
were taken and when, in addition, a very high grade of di- 
mensional accuracy was adhered to, the quantity of output 
was astonishing. 4 The fact that these enterprises dealt 
with large-scale interchangeable manufacturing in no way 
weakens the general applicability and truth of the principles 
involved ; which serves to show that the method of planning 
for large output at low cost with quality as the basic and 
primary guide is more than vindicated by the results. 

Control of Quality Basic 

The facts demonstrate that when manufacturing ar- 
rangements are made first and primarily with the intention 
of controlling manufacturing to definite and uniform stand - 

4 Typical examples of war time production successes are set forth in Chapter XII. 



20 THE CONTROL OF QUALITY 

ards of quality, quantity of output will follow. Briefly, if 
we first take care of quality, quantity will take care of itself. 

This does not mean that there is no need of the various 
modern devices for increasing and controlling production, 
because all of these things have their place. What it does 
mean, however, is that quality should be the basic guide and 
that, like quantity, it is an integral part of all the manufac- 
turing operations and demands recognition accordingly. 

In this connection the effect of losses of work in process 
on quantity of output alone is all too frequently overlooked. 
These losses seriously affect production in a direct way, but 
they still more seriously slow down production, reduce out- 
put, and increase cost in certain indirect ways which are 
much less apparent and hence, by reason of this obscurity, 
more difficult to detect and to remedy. A piece that is 
wholly spoiled represents a loss of all the work expended in 
its manufacture up to the point of spoilage; yet, even so, its 
outright loss is frequently cheaper than a partial injury 
which requires the attention of the best men in the shop to 
repair the defect, while their regular work meanwhile is at a 
standstill. In other words, the generalization that it is 
always easier to do a thing right in the first place, holds 
equally well in the factory. 

The Quality Bonus 

As further indications of the trend toward recognizing 
the value of the quality approach, a few cases may be cited 
where managers have had the courage to go so far as to 
establish a wage payment based definitely upon quality. 
Even when a quality bonus is superimposed upon a piece 
work system which contemplates payment for good work 
only, the results obtained by a separate payment for quality 
have been astonishingly satisfactory. In two instances 
which were merely isolated mechanical operations, where 



INTRODUCTION 2 1 

the rejections were exceedingly numerous, shifting the piece 
work rate to a reward for quality reduced rejections to a 
negligible amount almost overnight. The following exam- 
ples, however, deal with quality bonus payments which are 
in effect on a much greater scale, and which represent a radi- 
cal departure from currently accepted practice. 

Experience of The Shelton Looms 

Some time ago The Shelton Looms, under the progressive 
control and guidance of Sidney Blumenthal, established a 
quality bonus for weaving. This mill is engaged in making 
high-grade, deep-pile silk and woolen fabrics and of course 
a great deal of attention is paid to quality. At a certain 
stage of development the manufacturing problem was ap- 
proached from a new angle, and the quality bonus for weav- 
ing was adopted. The improvement in both quality and 
quantity is indicated by contrasting the following figures 5 
(which are for the first quarters of the years stated) : 

1917 1920 

Number of men 1 ,784 1 ,645 

Hours per week 50 \ 47^ 

Yardage 107 154 

Quality 73*% 90+ % 

Mr. Blumenthal has been quick to take advantage of 
suggestions for improving management methods and to 
follow them up with care. Consequently, it is interesting 
to note that he summarizes the experience of his company 
in the matter of paying for quality by saying, "Attention 
to quality demands thoroughness, and thoroughness removes 
the obstacles to production." 

Experience of the Armstrong Cork Company 

As a further example in the field of wage payment based 
primarily upon quality, the experience of the linoleum divi- 

5 Furnished through the courtesy of L. DeK. Hubbard, Operating Vice-President, and 
F. Stolzenberg, Mill Manager of The Shelton Looms. 



22 



THE CONTROL OF QUALITY 



X^c $*0t*cr&ti$ w 'm u , 



l_ IT ^ 



or 

OUR. 

ARTIST 





THE FASHION DCPT 
GETS Of*l TNt JOB, 
ANOOOSTU MB 5 
ARE fWPS, 

expensive 

DRAWlN(r5 
& PHOTON 
ARE MftPE 

T6 Sh o«*s/ 

THE OOOOJ 
To THE BEST 
AO VANTAGE. 



THE MPiMOR^CTOPimO 
OEPT PUR<HAS£S 
THE A<\ATe&l ALS 
AND SCNEOULES 
-THE UOOMSAHP 
/r\ACHfME3 
TO MAKE. 
THE 
GOODS. 7 >vf 





THE- .SALES DJEOT 
G£T5 , N A STACK 
QFOCJDER.S 
THAT WOUUO 

Fie.'^s 

JEALOUS- 



<f^5*r^)THE DYER 
\iyc>oEi imOT 
fbLi.ov>/ 

HIS 

FORMULAS' 
.CAREFULLY 

flMOOOM 
A.r>l D T HE .«• 

Ojj;/MSyAC 

AFTCT/aaO 

THRM 

CAGE 



THE ACTUA1. 
PRO DO CTf a a» 

IS - STARTED, 
BOT THE. 

w/o. «-f e r. 

IS «be- 

1_65J ANt 

lets 

DEFECTIVE 

yA.R.AI 

<jO IMTO 
HER WARI 
RATHER. 
THAN STOP 
-To F'* 

thc^n. 




THE WEVSCs^E (e, 
"WINKS HIS - EYTE 
AT iI*APER.F.ECt>OIM5 

zvmo «-£Ts--rHeA\ 
go RATHee- 

Th 4Arsj to 
5YOPTH6 
l_oor-A 
x-ofWG 

eyvjO'JO H 
To l?£PAl6. 
6ROK.BN 

THREADS'. 





FlMALWY.THE 
EVAMINEt. poESNT 
WANT TO BE TOO 
WAOOO/-I THEE 

wEAveie, ano 

THE SHlPPlNO CLERK 
FV1.CKS THE OOOD5 






THE 1 

MAMVJ FACTORING- 

Der>A«?TAiej>JT 

<5 <J«A»LE. 
TO 

IA-(PX?OVE 

IT, Jo 



THE FINISXKP 
PRODUCT IS 

(?eceiN/ce e»y 

THfiCl/STOMtK 
WHO 13 

•3s So 

fS -J DlSQLI STfO, 
\ P> DtrAPPolXilEP 
jffiP AMD 

EajRaGED- 






HE: will ACCEFT 

THfM OMUYW 
Such acom<-ess- 
Ioai /ai PRice" 

THAT IT 

eecowes 



coi^pLerre 

tosr. 




AFTTCCa Tt-tlS' 
CRUSM'NQOEFEAT 
N»W 0UALITIES 

AfNt? Schedules 
MUST BE DEVISED 
TO TAKE THE; 

PLACE Of THE 
eu»MEiP ^. 

O/SEi, ANDy^J 

c 




THE BOOi^E«AM O- 
FVM-I- S ♦ 

THE WAEPEH- 

tue. w/EA-vtsie.- 
Ttie OY6IB — 
T*JS F/NISHEP- 

T«e E>cA^i/Mi=r? 
THE 3MIPP/M0 n-eex 

AN O 

EVERY BOD-V ELSE, 
W«OtEf«T 
OR. 
GO I l_T V 
ARE "LAID OF-P" 

THE. B©Of>A.eP,A,/vjO 

C<*nes back, » 



M< 



WoR^lS il)SPENX>SD 

Ti-ifi fACToRYDUE 
ietS3/ARy CHANCES 

MRCHrNKRy 




Figure 3. An Object Lesson in Quality 

Drawn by an employee of The Shelton Looms. 



INTRODUCTION 23 

sion of the Armstrong Cork Company, Lancaster, Pennsyl- 
vania, is equally interesting. 6 As everyone knows, "battle- 
ship linoleum" is a standard product of established quality, 
and it is natural that its makers should view the matter of 
production with quality as a guide. 

The bonus system for quality production was conceived 
and installed in 19 14, and has been in successful operation 
ever since. The primary object of the plan was to decrease 
the quantity of seconds produced and at the same time to 
guard against a decreased production per man. The result 
has been a consistent increase in quality each year, so that 
from the early part of 19 14 to date the increase in output 
of first-quality goods is 30 per cent greater than when the 
quality bonus was started. 

During this period the production per man increased 
slightly, but this was not one of the motives for installing 
the system. Since production in this industry is deter- 
mined almost exclusively by the speed of given machinery, 
the special aim was to see that the production governed 
by the speed of the machines was not reduced by the efforts 
of the men to turn out perfect goods. This has been suc- 
cessfully accomplished. In fact, during the war period 
when the man-efficiency in industry generally reached a very 
low ebb, the experience of this plant was the exact opposite, 
for the efficiency per man throughout the various depart- 
ments increased perceptibly. This experience under the 
trying conditions of the period in question is a further vin- 
dication of the managerial judgment which makes quality 
the basic criterion for attacking production problems. 

Decreased Selling Costs with Quality Goods 

The results obtained by The Shelton Looms and by the 
Armstrong Cork Company certainly warrant a wider study 

8 From information supplied through the courtesy of John J. Evans, General Manager. 



24 THE CONTROL OF QUALITY 

and application of quality payment ; for, in addition to im- 
proved quality itself, the resulting increase in production 
means decreased costs — both directly and through the elimi- 
nation of various sorts of losses. 

There is, moreover, another phase of lowered cost when 
quality receives attention, which should not be overlooked, 
and that is the lessened selling expense which is a direct 
result of supplying goods of standard quality. Such arti- 
cles sell themselves at the factory. 

There is evidence on every hand that the purchasing- 
public is applying much finer and more intelligent discrimi- 
nation in its buying. Even the non-technical press is full of 
advertising matter setting forth in detail the reasons why 
the goods advertised possess the characteristics claimed for 
them. In other words, the average purchaser is becoming 
a better inspector. Consequently, work which is held to 
standard is being more and more appreciated and the sale of 
such merchandise is immensely simplified. 

The element of quality enters into a number of things 
which are not a part of production. When the buyer realizes 
that nobody else's goods come to him as well packed or in 
such an economical form for him to handle, it is easier to 
sell to him. So quality enters into packing. And it is not 
a far extension of this idea to say that quality enters into 
shipping as well ; because prompt deliveries by the cheapest 
routes are certainly factors which are influential in the repu- 
tation of your goods almost as much as the satisfactory 
quality of the goods. Also, quality in "service" generates 
reliance in the firm which really stands behind its goods. 

In fact, anything that tends to control quality to more 
definite and satisfactory standards, whether in the goods 
themselves or in service connected therewith, increases 
selling power just that much. Thus the statement that 
quality goods are sold at the factory becomes a reality. 



CHAPTER II 

THE APPROACH TO QUALITY CONTROL 

The Starting Point — Determining Nature of Product 

Quality, being a characteristic or group of characteristics 
of a product, is intimately a part of the product. There- 
fore, the only safe and orderly starting point for any en- 
deavor to bring quality under exact control is the product 
itself. We may be sure of successful results if we begin at 
this point. This procedure differs radically from the usual 
approach when quantity production is sought directly. In 
the latter method of attack on the problems of manufactur- 
ing there is an ever-present tendency to begin with the sta- 
tistics of the business. Records of past production, esti- 
mates of future production, and calculations as to what 
equipment, tools, materials, and labor are necessary to se- 
cure an increased quantity are brought to the forefront. It 
is only later that consideration is given, if time permits, to 
matters affecting routing, processing, inspection, and others. 
Now the product is a final result of the orderly and co- 
ordinative working-out of all these things. Each makes a 
plus or minus contribution to quality. So the control of 
quality demands that the quality standards be determined 
first, and then that all the arrangements for creating the 
product be so made as to insure the realization of these 
standards. This means nothing less than shaping the means 
to produce the desired end, instead of permitting manufac- 
turing system, methods, and what-not to determine the 
character of the factory output. 

As L. P. Alford l has frequently stated in his excellent 

1 Editor of Management Engineering. 

25 



26 THE CONTROL OF QUALITY 

analyses of management problems: "The end of manufac- 
turing is the production of goods." Let us select what we 
intend to make first, and then take up the processes, work- 
ing arrangements, organization, and system necessary to 
achieve that result ; for it is by the results and not by the 
means that our work is judged. 

This procedure distinctly stresses the fundamental im- 
portance of establishing definitely the standards of quality 
which are to be followed, before we can know exactly what 
we are trying to make ; for if there has been found any vir- 
tue in preplanning for production, it has been demonstrated 
that the more completely we know what we are trying to do, 
before we actually start doing it, the more easily and swiftly 
will the work be carried out. It is this wider idea of quality 
which exactly describes the features of a design with which 
we are chiefly concerned. 

The Commercial Factors — Requirements of the Consumer 

Quality, therefore, as referred to here, involves a very 
definite specification of the important characteristics of the 
product which enable it to fulfil the needs and demands of 
the customer in a satisfactory manner. The customer re- 
quires that the article be suitable for his purpose. That is, 
it must be reliable, it must be durable over a period of time, 
it must be economical both in first cost and in operation, 
and usually it must be pleasing to the senses as well. 

The Design — Securing Consumer's Requirements 

From the standpoint of the designer each of the com- 
mercial factors is created by the various features of materials 
of construction, shape, dimension, finish, and so on; and the 
quality of the final result is determined by these as well as by 
the degree of precision with which the design standards 
are realized. This involves processes and workmanship. 



THE APPROACH TO QUALITY CONTROL 27 

Needless to say, the product should be designed to meet the 
commercial requirements as nearly as may be consistent 
with economical manufacture; and in doing so the manu- 
facturer is faced with the necessity for compromising in 
almost every instance. To solve the problem intelligently 
requires a knowledge of what we are trying to produce and 
why. The quality may be anything we choose, but as a 
starting point a clear idea of what we seek to accomplish is 
fundamental. 

As an example of this process, what is so simple as an 
alarm clock? Like all other clocks an alarm clock may be 
expected to keep reasonably good time over a period of 
time. That is part of its job as a clock. But beyond that 
it has a very unpleasant duty to perform. It should begin 
with as gentle a tone as possible and still accomplish its pur- 
pose with certainty. Having attracted attention, the more 
pleasing its appearance the less likelihood of trouble. The 
least the manufacturer can do for an alarm clock is to pre- 
pare it for this part of its job, so he gives it a fine finish in 
nickel plate. 

Now a certain manufacturer took great pride in the fact 
that he was making the cases of his clocks out of a high 
grade of brass, but he overlooked for the time being that the 
quality of the brass in the case was of no interest to the pur- 
chaser whatever. His real job as manufacturer was to 
provide a nickel-plated surface which would stand ordinary 
alarm clock service. When he investigated the matter from 
this point of view he discovered that a cheaper grade of 
brass would take a better nickel plate and hold it longer 
than the higher priced material he was using. Thus you 
will observe that the manufacturer, having first studied his 
product from the standpoint of the commercial factors in- 
volved, learned what he was trying to produce and why. 
This led him at once to the conclusion that he should carry 



28 



THE CONTROL OF QUALITY 



the problem to the manufacturer of raw materials, who might 
reasonably be supposed to know more about such materials 
than anyone else, with the direct result of an improvement 




Figure 4. A Common Method of Holding a Micrometer Caliper 
Courtesy of Brown and Sharpe Manufacturing Company. 



in quality accompanied by an actual economy in produc- 
tion. 

We are pretty sure to be on safe ground if we understand 
that quality requires • accuracy and care, and that these 
things are less expensive than their opposites — inaccuracy 



THE APPROACH TO QUALITY CONTROL 29 

and carelessness. Consequently, if it has been decided that 
the commercial requirements of the case call for a low-grade 
product, let us proceed on that basis but with the determina- 
tion that the lower standards of quality are just as delib- 
erately and intentionally selected as if they were of higher 
grade. 

Provision for Improving Design 

As has been pointed out, economy of manufacture and 
uniformity of quality standards go hand in hand ; but there 
is no reason why the standards should not be raised from 
time to time without conflicting with the requirement of 
uniform standards during any one period or season of manu- 
facturing. One of the desirable advantages of paying 
special attention to quality is that this method constantly 
reveals chances for improving quality without increasing 
costs. The stage is not likely to be reached where further 
advances are impracticable. 

The manufacturer who is satisfied that his product can- 
not be improved is in a dangerous state of mind, because 
progress has not stopped in any art or in any science. If he 
thinks that the limit of improvement has been reached with 
the means available, then it is time to look for improved 
methods, because no business should stand still in any sense. 
Ordinarily when an art is not advanced, the reason is to be 
found in failure to provide, within the organization, for 
systematic and progressive improvement. Further, when 
someone says that the thing is impossible, that very thing 
provides an opportunity; for "the man who says that a 
thing can't be done nowadays, is pushed out of the way by 
someone doing it!" 

From the design standpoint, the best way to provide for 
the systematic advance of quality, is to realize at the start 
just what the departures from the highest standard are going 



30 THE CONTROL OF QUALITY 

to be. Picture a lower grade product from the viewpoint of 
a de-graded high-grade article, in which the reductions in 
quality are known and have been made deliberately and 
with "malice aforethought." Then we are in a position to 
know the directions in which improvements can be made, 
and in great detail. 

The path of future progress is thus made clear, and it 
will be found that the process of gradually refining and im- 
proving the product, step by step, will bear fruit presently 
and quite rapidly. 

Materials 

After the product has been thoroughly analyzed with 
reference to the qualities which it is desired to secure, and 
after the design has been carried through the stages of com- 
promise made necessary by considerations of economy, the 
next step is the selection of materials of construction. Now 
the raw material of one manufacturer is the finished product 
of another. The manufacturer of the raw material has been 
through the same process of analysis and economical com- 
promise. Hence it is not reasonable nor even possible to 
select materials which are ioo per cent right for our purposes, 
and we are faced again with the necessity for making up our 
minds. In fact this is just one step in a long series of com- 
promises, all flowing from the fact that quality is something 
which is peculiarly subject to change and variation. 

Since uniformity of result is the thing sought, the most 
desirable characteristic of the raw material, other things 
being equal, is uniformity. Once more, cost becomes a sec- 
ondary issue, within reasonable limits of course. In the 
case of brass for alarm clock cases, it was noted that a 
cheaper brass took a more permanent and uniform nickel 
plating. But the same demand for uniform results, or for 
ease and certainty of working up the material may justify 



THE APPROACH TO QUALITY CONTROL 



31 



a higher cost. Thus it is currently reported that the lowest 
priced automobile made today contains the highest per- 
centage of alloy steels, as a matter of economy. 

Processes 

With raw materials decided upon, the stage is reached 
where processes must be studied with the same mental atti- 
tude. Can the processes and their equipment possibly pro- 
duce the results which are desired? If not we should cer- 
tainly understand just how they should be changed to bring 
the work to our predetermined standard, with economy. 

It will invariably be found that certain approximations 
to the standard are necessary. In other words, the con- 




Figure 5. Measuring a Turned Piece in Lathe 

Illustrating another correct way of holding micrometer caliper. Courtesy of Brown and Sharpe 
Manufacturing Company. 



32 THE CONTROL OF QUALITY 

sideration of the problem requires another compromise as 
soon as the selection of manufacturing processes is made. 
This fact holds true no matter how sensibly the processes 
are selected or how simple they may be. Quality varies, 
and the design must be modified accordingly to suit the 
processing, by stating the permissible variations from 
standard which will be tolerated. The idea of tolerances 
and limits for variations from standard thus enters the man- 
ufacturing scheme. Whatever the other conditions may 
be, the processes must be chosen to permit reasonable 
control of the resulting work to the degree of uniformity 
allowed by the tolerances in question. 

Workmanship 

Intimately associated with the study of processes is the 
matter of workmanship, which involves all questions asso- 
ciated directly or indirectly with the proper application of 
the machinery provided for production. It is not infre- 
quently the case that the foreman says his tools are all right 
because he has personally used them to make satisfactory 
articles. On the other hand, all he has proved by using the 
tools himself is that an expert workman can get the results 
with the equipment available. But the only labor obtain- 
able for using these tools may be quite incapable of attaining 
equally satisfactory results without changing the tools or 
without very careful instruction, or without change in the 
surrounding conditions of inspection or other means in use 
to safeguard the production. "Transfer of skill" and "the 
promotion of personal effectiveness" at once come into 
action. 

Operating Organization and Records 

Evidently this same process of intensive investigation of 
the manufacturer's problem from the standpoint of quality 



THE APPROACH TO QUALITY CONTROL 33 

will now carry us to the study of the organization for operat- 
ing the factory and finally to the system of records of per- 
formance, which are used in controlling the organization in 
a way to result ultimately in production in accordance with 
the quality standards as set. It goes without saying that 
each and every factor entering into the production problem 
requires sufficient study to insure definite ideas as to how 
each of these factors can be positively and separately con- 
trolled. When this control goes into effect in the qualita- 
tive refinement of the industry, production problems for 
the most part will be found to have been solved in the proc- 
ess, simply because quality is so fundamental in its nature 
that it requires a consideration of all the factors involved in 
the business. 

Inspection an Essential 

If we were starting a new project the preliminary study 
of quality which has been outlined in the foregoing pages 
would be made before and during the starting of the factory. 
Once manufacturing has begun, however, the same continued 
investigation must be supplemented and assisted by some 
sure method of bringing to the surface information relative 
to the errors and failures to attain quality standards. 

This is a situation in which every factory finds itself. 
The factory is running along under pressure of production, 
and quality is always tending to slip away from the stand- 
ard and to get out of control. Consequently there is an 
urgent need to bring to light immediately, and to evaluate 
the deviations from the desired quality, in order that prompt 
steps may be taken to limit and correct them. 

As an instrument for the prompt and perpetual analysis 
of the quality situation, and thus for assisting in the control 
of quality, a proper inspection service is necessary. But to 
render such service, as well as to carry out its many other 



34 THE CONTROL OF QUALITY 

important functions, the inspection department must be 
placed in a position to act effectively. That is only com- 
mon sense. Yet the fact remains that there is a very general 
failure to appreciate the possibilities of inspection, although 
war experience has helped considerably to dispel this lack 
of appreciation for what inspection can do if given a chance. 
The subject is one which has received far too little atten- 
tion from the standpoint of systematic study. There is 
practically no literature or philosophy of inspection. In 
view of this situation let us now examine some of the various 
characteristic peculiarities of inspection as an introduction 
to the further study of quality and of methods for the con- 
trol of quality. 



CHAPTER III 

INSPECTION— THE NEED FOR INDEPENDENT 

SCRUTINY 

Maintaining Standards — Measurement and Control 

To set up standards of quality, no matter how thor- 
oughly and carefully it is done, is one thing; but to realize 
those standards in the actual work in the factory is quite 
another thing, for the mere stating of what is wanted will 
not secure the result. Suppose that a design has been 
proved out in a thoroughly satisfactory working model or 
that an article is found to be acceptable to the market; 
that the working standards have been determined with 
experience based on the best practice and guided by the 
highest mechanical engineering skill ; that the equipment is 
adequate and installed in keeping with the requirements of 
economical and high-grade manufacturing; and then sup- 
pose that the factory is started to operate with nearly all 
work on a piece rate or similar basis, with schedules of 
desired daily output in the hands of each department 
head — in short, with the usual great pressure for quantity 
production. Under these circumstances will the product 
measure up to the working standards of quality so carefully 
determined and clearly described? Certainly not, unless 
means are provided for measuring the quality of the work as 
it is made, together with the necessary organization for 
seeing that the work is held to standard within economical 
bounds. 

To control quality so as to realize the working standards 
as nearly as may be, requires both logical thinking and 
masterly management. The seriousness of the task in- 

35 



36 THE CONTROL OF QUALITY 

creases rapidly with the degree of accuracy or grade of 
quality required and with the complexity of the product. 
It is made still more difficult if the manufacturing opera- 
tions are conducted on a large scale, for this is one of the 
things which becomes magnified in the large plant in a ratio 
that increases much more rapidly than does the size of the 
plant itself. 1 There are certain problems which are solved 
in the small shop with comparative ease, because of the di- 
rectness with which they can be seen and the simplicity 
and promptness with which they can be handled ; yet these 
same problems become serious difficulties in the large 
plant. 

When we are surrounding the work as it flows through 
the factory with an environment that makes for quality 
production, someone must exercise the duty of viewing 
the work closely and critically so as to ascertain the quality, 
detect the errors, and present them to the attention of the 
proper persons in such a way as to have the work brought 
up to standard. This function of carefully scrutinizing the 
work as it progresses through the various stages of manu- 
facture, and of pointing out the unsatisfactory work, is the 
principal purpose of inspection; and by "inspection" is 
meant inspection conducted as a function of the factory 
organization, and not by some outside organization em- 
ployed by the purchaser. 

The Instrument for Measuring and Controlling 

One of the first things brought to light by a study of the 
problem of measuring the quality of work and establishing 
the necessary organization to secure and maintain this 
quality is the fact that inspection is, first, the instrument for 
quality measurement, and second, that it is a powerful 
factor in quality control. It is like the keystone of the arch. 

1 "Production as Affected by Size of Plant," by G. S. Radford, Management Engineering,^ 
Aug. 1021. 



NEED FOR INDEPENDENT SCRUTINY 



37 



I 
« i f ' ;A 


- 








«•"_"■ > 


| 




yr=r? - r .v 1 .*.'■" '& 




I -1 

1 

Jr m 


I 1 


I 


'flY^ tt .._' '.Agjfl 


I 






| t-m . 


1 


I 


- ifci'f 


I i^" JllL- 1 




■d 




,£3jiiL— . ' .' £< 


44 > 1 £s 




f 3 


> 


Ki .... g^j jgj 


E\$^M 


Hft JBW,i * ^' : H HEii-X 


*^N^** 




# **^Mr 


^^W ***** 




^ 






f , ^ , ^ 


^1 ■ ..' J| 


\; 






; ^lV\ 


lip 






, IB 



Oh 



38 THE CONTROL OF QUALITY 

You can get along without it, but the supporting false work 
which must be left to take its place is crude, clumsy, less 
effective, and more costly. 

Its relation to quality is indicated by this thought. 
Quality may be likened to a globule of mercury — it is al- 
ways tending to slip away. You can hold mercury in a 
given position or on a particular line with a certain degree 
of success without resorting to control. In the same way it 
is possible to secure quality of a certain kind and degree 
without inspection, but in the factories which stand as 
leaders in their respective lines there is always a well- 
developed, scrupulously maintained inspection service. 

Convincing the Management 

Every chief inspector must first realize, with entire 
conviction, that inspection is a necessary step in the great 
process of manufacture. Then it becomes his painful duty 
to get this idea across to the management. The latter task 
is usually difficult. The inspector is responsible for quality 
to a very great extent; he is the management's guardian 
against spoilage and waste; and when quality slips he is 
conveniently at hand to receive the blame. In many plants 
where his true relationship to quality is not clearly under- 
stood, this latter "duty" of receiving the blame for errors in 
work constitutes a large part of his daily job. 

That such an attitude toward the inspector is untenable 
is proved by a moment's reflection on the fact that the in- 
spector never puts his hand to the work except to look it 
over or to measure it. The inspector enforces quality by 
refusing to accept poor work, but this act of rejection is 
passive as regards enforcing the production of good work. 
The quality or lack of it must necessarily be worked into the 
material by the production department which controls 
production processes. How then can we blame the in- 



NEED FOR INDEPENDENT SCRUTINY 39 

spector for lack of quality? In this regard his duty is com- 
plete when he passes upon the quality characteristics of the 
goods and reports his findings. It may be noted parenthet- 
ically that this very fact is one of the reasons why quality 
cannot be placed under control until every department of 
the factory has been reviewed from the quality standpoint 
and brought into proper alignment and co-ordination. 

Growing Importance of Inspection 

The kind of inspection, the manner of its application, 
and the extent to which it is used are conditioned, of course, 
by the circumstances in each case. One must first deter- 
mine what it is desired to accomplish by inspection and then 
consider the several different ways in which the desired re- 
sult may be obtained, always with a view to selecting the 
most economical method. There is such a thing as too 
much inspection as well as too little, but a proper degree of 
inspection is always an economy because it stops leaks by 
the early detection of errors and thus prevents unnecessary 
loss. From a strictly business standpoint it is justified as an 
insurance of that part of "good-will" which is cultivated 
and retained by the delivery of goods made to a definite 
standard. 

The evolution of inspection is both interesting and il- 
luminating. In early factory practice (and, for that mat- 
ter, in many plants today) inspection involved merely look- 
ing at the work. Dimensions were scant or full. Then 
through a gradual development, following in step with the 
attainment of greater accuracy in the mechanical arts 
which was made possible by more accurate measuring de- 
vices and better machinery, we began to measure in 
hundreths of an inch, then thousandths, then ten-thou- 
sandths, and now in hundred-thousandths, if necessary. 
Such progress in material ways calls for adequate and 



40 THE CONTROL OF QUALITY 

similar adjustments in organization; but the development 
of an inspection force within the factory organization, and 
hence paid for by the manufacturer, has not kept pace with 
the technique of manufacturing except in a rather limited 
way. 

The fact is that inspection in the past has been applied 
in many cases by the purchaser, and often, especially in 
government work, in a manner to give rise to the feeling in 
the manufacturer's mind that inspection should be regarded 
as a necessary evil. Without question, a purchaser's in- 
spector can cause ruinous conditions in any factory, es- 
pecially if there is a lack of practical control, and if the 
specifications and other data under which the work is being 
performed are inexact or conflicting. 

Inspection Often a Necessity, Always an Economy 

It is generally recognized that it is a paying proposition 
for the large purchaser of materials to provide his own in- 
spection force. Yet it is even more to the interest of the 
manufacturer to establish an inspection organization for 
himself. He gains all the advantages secured by the pur- 
chaser and many more besides through his ability to control 
and direct the activities of his own inspecting force into the 
channels most useful to him. 

If you who are neither an architect nor a builder are 
about to erect an expensive house or construct a new factory 
building, do you inspect it yourself or do you employ some- 
one who is competent? Of course you adopt the latter 
method and consider the money expended for supervising 
the inspection well spent. You do this no matter how 
trustworthy or careful or reputable your builder may be. 
Now consider carefully why this expenditure is a good 
business proposition, and then apply the reasoning to your 
own factory. You cannot make everything yourself, nor 



NEED FOR INDEPENDENT SCRUTINY 41 

even view it in a cursory way; nor can your superintendents 
and foremen, for they are occupied with many other things 
principally connected with human relations and quantity of 
output. The average workman himself is least of all 
concerned with safeguarding the quality of your product, 
unless you make special provision to keep his work up to 
standard. In many cases nowadays, he has not the ability, 
of his own motion, to furnish the result you desire. Thus 
inspection becomes, oftentimes, a necessity. In any event 
an inspection service properly adjusted to the needs of the 
case, is an economy as well. 

Comparatively few factories had their own inspection 
services prior to the war, but many of those operating under 
war contracts were forced to provide such service as a mat- 
ter of protection and have learned thereby its value. It is 
to be hoped that much of the old and prejudiced attitude 
toward factory inspection as an expense to be avoided if 
possible, has disappeared; and that there will be realized 
the large return in both quality progress and decreased 
costs which are made possible only through the applica- 
tion of a proper system of factory inspection, and not 
otherwise. 

Need of Intensive Study of Inspection 

Inspection, to be sure, is only a part of the control of 
quality, but it is an essential part. For quality can be 
controlled properly only through a factory inspection serv- 
ice — adequately organized and applied with an apprecia- 
tive understanding of the philosophy behind it. 

Inspection is being more generally used than ever before, 
but is its function thoroughly understood? At present 
there is evidence that inspection methods in many plants 
are being overhauled to meet the oncoming and more critical 
demands of commerce. In some cases, inspection depart- 



42 



THE CONTROL OF QUALITY 




NEED FOR INDEPENDENT SCRUTINY 43 

ments as such are being provided for the first time, and 
existing inspection is being brought into line with the 
best modern practice, for closer acquaintance with a good 
inspection service is bound to prove its sound business 
value, not only in raising quality but also in lowering costs 
and increasing output. 

In view of this situation one might expect to find con- 
siderable attention being paid to the theory and practice of 
inspection, but the engineering profession has been slow to 
give it the same serious study that it has shown in other 
lines of work. For example, the last ten years have wit- 
nessed the intensive development of a literature concerning 
itself, from the standpoint of the engineer-executive, with 
the business of management in all its details. This litera- 
ture is full of references to standards of quantity of output 
per man per day, and contains countless methods, schemes, 
and devices for increasing output and decreasing cost, all by 
the route of laying stress primarily on quantity. Much is 
said about how to determine the proper standards for 
quantities of output under given conditions. Much more 
is said about how to attain these standards of quantity 
through all the varied means management engineering has 
developed ; for while it is a difficult task to determine just 
what the standard quantity of output should be; by the 
same token it is much more difficult to put these standards 
into effect; just as it is harder to keep trains running on 
schedule than it is to lay out the timetable. 

Study of Theory Needed 

But with all this intensive study of industry, how little 
attention is paid to the discussion of how to fix upon and 
realize standards of quality in production, and the relation 
of inspection to this problem! The Society of Industrial 
Engineers recently, and very properly, defined the activities 



44 THE CONTROL OF QUALITY 

under which candidates for membership shall qualify. 2 
Some twenty industrial subjects were listed. An examina- 
tion of the subjects so set forth indicates that no mention is 
made of inspection, and that little if any consideration has 
been devoted to quality control in production — certainly 
nothing like the attention devoted to questions principally 
affecting quantity of output. This, moreover, is merely 
typical of the general professional attitude, although this is 
not the first time that something has been used practically, 
before the underlying theory has been investigated. Plan- 
ning was always done in effect, but it was not performed 
with the greatest economy until the engineer separated it 
out of manufacturing as a whole, for individual and exhaus- 
tive inquiry. 

Can we afford in this instance, to neglect so important a 
matter any longer, especially in the face of existing condi- 
tions? The answer would seem to be strongly in the nega- 
tive. The size of modern inspection departments alone 
would warrant careful investigation of the subject. In 
many well-established plants 5 per cent of the entire work- 
ing force is employed in the inspection department and fre- 
quently the percentage is considerably higher. In many 
cases it could be made higher with advantage, until quality 
is under such control that the amount of inspection can be 
reduced. 

Further, the sphere of influence of the inspection service 
is far greater than its numerical relationship, for it reaches 
into every department and touches all the detailed factory 
operations having to do with creating and maintaining 
quality standards. These facts alone, it is submitted, 
should indicate the need for careful study of the theory and 
practice of inspection, by all who have to do with the 
management of industry. 

2 Industrial Management, Jan. 1920, p. 55. 



NEED FOR INDEPENDENT SCRUTINY 45 

Functions and Limits of Inspection 

If one is going duck-hunting it is just as well to take 
along a shot gun, but having the gun does not mean that the 
hunter will return with a bag of ducks. Unhappily this 
truism holds for many things besides duck-hunting and 
leads to frequent misunderstanding of the inspector's 
function. It has its limitations like everything else. Its 
purpose is to measure quality and in this and in other ways 
to assist in quality control ; but it does not create quality. 

In this preliminary study of the need of inspection it 
should be noted finally that inspection itself is not a fixed 
and definite function or process except as regards the prin- 
ciples which are involved. In contrast to being fixed, it is 
very flexible and may be applied in many different ways. 



CHAPTER IV 

THE TYPES OF INSPECTION 

Conformity with Special Factory Situation 

The factory is guided toward production in accordance 
with the working standards, by inspection, which measures 
quality, applies discriminating judgment in close cases, and 
in short forms an environment that continually sorts out 
defective work while allowing satisfactory work to proceed. 
Naturally the kind of inspection most suitable for a particu- 
lar situation depends on the character of the work, the 
standards of quality, the skill of the workmen, and similar 
matters relating to the given manufacturing conditions and 
circumstances. The thoroughness of inspection varies 
from a casual viewing of samples taken at random in the 
shop, up to the analysis, testing, or careful measurement in 
separate inspection rooms, of each part after each mechan- 
ical operation. In large plants engaged on high-grade, 
interchangeable work, almost every one of the many pos- 
sible kinds of inspection will be needed at some stage in the 
process of manufacture. 

Material Inspection 

Little need be said of the inspection of raw materials. 
The development of highly standardized material specifica- 
tions has been made possible through a previous and pro- 
gressive development in applied physics and chemistry. 
The methods of the physical and chemical laboratories 
which originated the data for the standard specifications in 
the first place, are thus available in turn for testing and 
analyzing the materials themselves. It is most unusual to 

46 



THE TYPES OF INSPECTION 47 

find a plant of even moderate capacity without some sort of 
laboratory in which samples of each lot of raw material 
received by the stores department are carefully inspected 
before being passed for issue to the factory. 

A chemical works with a single product as simple and 
cheap as silicate of soda has its own laboratory for inspecting 
both raw materials and finished product. A flour mill using 
the method of mixtures to secure a definite quality standard, 
measures in the laboratory the food values of each lot of 
grain, in order to secure data for the proper balancing of its 
output. A paper mill makes microscopical examination of 
fibers. In a great metal-working plant we find an assem- 
blage of thoroughly equipped laboratories — chemical, physi- 
cal, and metallurgical. So it goes throughout the great 
range of the arts. Even small shops may avail themselves 
of facilities for inspection of materials by patronizing the 
commercial testing laboratories to be found in every im- 
portant manufacturing center. 

When the local conditions are such that there seems to be 
no method or apparatus already in existence for this im- 
portant work, the scientist should be called upon to work 
out the problem. There is no reason today why means 
should not be developed to meet almost any requirement for 
inspecting and grading material. 

Office Inspection 

It is common practice, also, to provide an inspection 
service in the drafting-room, especially in the tool-designing 
section, so that the work of the "detailers" and other 
subordinate draftsmen is carefully gone over by the 
"checkers." It is perhaps not too far from our subject to 
note that the application of similar methods has been 
carried into large general offices in the form of an inspection 
of outgoing mail. When department heads sign outgoing 



4 8 



THE CONTROL OF QUALITY 



mail originating in their departments, it is not unusual to 
find a further checking up, through carbon copies of such 
mail being sent to the office of the general manager. 

Tool Inspection 

Factory inspection first appears in the tool-room. The 
value of a careful inspection of all special tools, fixtures, 
jigs, and gages, is quite evident, whether they are made in 
the factory's tool-room or purchased outside. If the tools 
are not correct, nothing is surer than that the work will not 
be correct. As an additional check on the tools, even if the 
work is simple, it is good practice in quantity production to 
make an inspection of the first piece (and the last) produced 
by a new machine tool set-up. A theoretically correct tool 




Figure 8. Some of the Special Equipment of the Tool- and Gage-Checking 
Room — Lincoln Motor Company 

West and Dodge lead tester and Shore scleroscope in foreground. 



THE TYPES OF INSPECTION 49 

may not produce correct work, due to some peculiar interre- 
lation between the tool and the way it is applied to the 
stock. In many cases this first-piece inspection may be per- 
formed by the mechanic who sets up the machine. This 
duty sometimes falls to a special inspection service, how- 
ever, if such a body exists. 

The subsequent periodic inspection of tools, and in fact 
of all manufacturing equipment, should be provided for 
systematically, so that nothing will be overlooked, special 
attention being given to the points where wear is rapid or 
likely to cause the most trouble. Where gages are in use, as 
in small interchangeable work, or when specially accurate 
measuring instruments are used, as on close work of a size 
beyond the accuracy of special gages or of too small a 
quantity to justify the cost of gages, then, of course, the 
greatest attention must be given to verifying gages or instru- 
ments. The questions which arise in gage-checking involve 
an individual practice, and therefore will be dealt with in a 
separate chapter. 

Process Inspection 

Coming now to the inspection of work in process, the 
first question to decide is where the inspection is to be made. 
This ordinarily involves either choosing between two types 
of inspection which are fairly well known under the respec- 
tive names of "floor-inspection" and "central inspection" 
or using some combination of the two systems. Floor- 
inspection means inspecting work at the machine or near it, 
while central inspection is the term used to designate the 
system under which the work to be inspected is carried to 
special spaces or rooms devoted entirely to inspection 
purposes. 

Central inspection involves the physical separation of 
inspection from production, but it may exist in any one of 



50 THE CONTROL OF QUALITY 

several forms. Convenience rarely permits all inspection 
to be centralized in one place for the entire factory, so that 
the ordinary method of using central inspection involves 
setting aside a place for it in one or more convenient loca- 
tions in each shop. 

Floor-inspection may vary from a sort of patrolling 
supervision which scans the work at the machines, up to the 
taking of very careful measurements and minutely scrutiniz- 
ing the work. It begins to merge into central inspection 
when the inspector is furnished with a special inspection 
bench or similar station located near the machines whose 
work he inspects. The inspection point may be located be- 
tween machines in the line of flow of the work, just as if it 
were a machine itself. If the separation between inspection 
and production is clearly defined, we have a distributed form 
of central inspection. In its most highly developed form 
central inspection implies that all of the work of inspection 
in a shop is centralized in a separate place, usually a room or 
enclosure, to which the work is brought. 

Advantages of Centralized Inspection 

The most evident difference between the two types of 
inspection is that, in one case the inspector goes to the work, 
while in the other case the work is brought to the inspector. 
But this apparent difference is by no means the greatest 
dissimilarity. Centralized inspection has characteristics 
differing markedly in many other and more important ways 
from inspection that is scattered by reason of being done on 
the site of the work. Central inspection, in general, per- 
mits the use of a less degree of experience and skill than floor- 
inspection, because the supervision of the work of the 
individual inspector is made easier. Frequently division of 
the labor of inspection is possible, and economy of inspection 
results. 



THE TYPES OF INSPECTION 



51 




52 THE CONTROL OF QUALITY 

Similarly the work of inspecting may be performed 
more thoroughly, as there is less likelihood of interferences. 
More important still, the inspector and the producer are 
not able to ' ' get together ' ' to anything like the extent pos- 
sible in floor-inspection. Accordingly it is much easier to 
control quality to definite standards, as well as to obtain 
a better control of the flow of work by means of central 
inspection, as will be indicated in more detail in Chap- 
ter VIII. 

Highly centralized inspection is the ideal type, for it is 
the specialization of inspection carried to the limit. Its use 
is not justified when parts are large or relatively few in 
number, nor when the production work requires such skilful 
mechanics that detailed inspection of their work is not re- 
quired. With massive work, of course, the inspection must 
be made at the place where the work is performed. As the 
size of the component parts of the work decreases, and 
transporting them becomes less difficult, a stage is reached 
when central inspection in some form is both possible and 
desirable. For example, the last or final inspection of large 
automotive engine parts would naturally be made in a 
separate room or space, through which the parts in question 
pass after being finished in the shops where they are made. 
In high-grade work of the same class it is good practice to 
remove these parts to the inspection room after each of a 
few operations in the course of manufacture. In this case 
the operations selected for central inspection are those in 
which close and complex work is performed, and whose 
influence upon succeeding operations may be very serious 
in accumulating errors. 

When many operations are used in making one part in 
quantity it is usually better to reinforce central inspection 
by a floor-inspection in sufficient quantity to locate costly 
errors more quickly. 



THE TYPES OF INSPECTION 53 

Inspection Combined with Remedy of Defects 

Inspection takes another form in many manufacturing 
processes where it is expedient to merge it with production. 
Ordinarily this involves an inspection for defects in combi- 
nation with the repair of the defects by the inspector. In 
the manufacture of fabrics, for example, the work may be 
rerolled on perches under the eye of an operator who repairs 
broken threads and similar defects as he finds them. A 
very simple case of allied nature is to be found in the testing 
of tanks, or water-tight compartments in ships. The por- 
tion of the structure to be tested is subjected to water pres- 
sure, inspected for leaks and "weeps," and the leaking rivets 
and seams caulked. 

Use of Special Mechanical Devices 

Inspection of large quantities of small pieces is some- 
times done economically by the use of special machines. 
In this kind of inspection, the operation is best considered as 
a part of the manufacture of the part. Strictly speaking, of 
course, no work is done on the part, inasmuch as the part 
is not changed by the process of inspection, although the 
quality of the factory output is improved thereby. The 
making of rifle balls and small cartridge cases offers examples 
of this sort. In one plant rifle bullets were carried on an 
endless belt (originally designed as a bean-sorting machine) 
before a number of inspectors, so that obviously defective 
ones might be detected easily and removed quickly. Simi- 
larly, cartridge shells with surface defects are more readily 
located by the use of special machines which roll them before 
the inspector's eyes in an endless procession. Scrutiny is 
made more certain by mirrors suitably placed in the ma- 
chine, to show all parts of each shell as it is rolled by. The 
opportunity for making an inspection operation more ef- 
fective and less costly is often revealed when consideration 



54 THE CONTROL OF QUALITY 

is given to developing mechanical devices to assist in the 
work of inspection. 

The Amount or Quantity of Inspection 

Intimately associated with the question as to the kind of 
inspection to be used, is the determination of how much 
inspection — a question that must be settled in the light of 
economy, for evidently we should provide the least inspec- 
tion which will accomplish the purpose. 

The necessary amount will vary, of course, with the prog- 
ress that has been made in the particular factory toward a 
better control of quality. If special attention is paid to 
quality, the amount of inspection can be reduced gradually. 
When this has been done, however, the inspection should be 
reconstituted before the manufacture of a radically new 
model is undertaken, for reasons that would not seem to re- 
quire detailing. 

In the first place it should be realized that the inspection 
department must use judgment — "horse sense" — without 
that it is only too possible for the department to tie the 
factory up tight. The abuse of inspection through having 
too many inspectors represents, of course, a dead loss from 
the direct cost of inspection. It is chiefly to be feared, 
however, because of the deadening influence on production 
of the attempt to get too large a percentage of the work up 
to standard. Incidentally this error will illustrate the value 
of a clear appreciation of inspection's function in the control 
of quality. 

Quality, as we have seen, is a variable. It is not practica- 
ble, therefore, to conduct manufacturing operations in such 
a way as to produce nothing but good work, i.e., work that 
is in accordance with the specified standards. Inevitably 
there will be some bad work. If inspection is applied with a 
view to reducing the amount of bad work to the absolute 



THE TYPES OF INSPECTION 55 

minimum, the effect will be to slow down the quantity of 
production to such an extent as to increase costs out of all 
proportion to the value of the few parts that might other- 
wise have become scrap. As a matter of economy, to do a 
certain amount of unsatisfactory work is practically neces- 
sary, paradoxical as this might seem on first thought. 

The Danger of Becoming "Fussy" 

In many cases where the standard is difficult to set 
exactly, and judgment must enter to a large extent, as in the 
case of inspecting for finish and surface defects, there is a 
fertile field for trouble of this sort. A factory manager, who 
was a man of unusually wide experience in many lines of 
interchangeable manufacturing and an alert and discerning 
observer as well, once said with reference to a case of this 
sort, " If you pass a hundred parts through the hands of a 
hundred (or even fewer) inspectors, not a single part will 
escape rejection. Every piece will be rejected by at least 
one inspector." 

This point of view was vindicated soon afterward in the 
following manner: A large quantity of sword bayonet 
blades were rejected for the alleged defect of not being 
straight, especially near the pointed end. Perfect straight- 
ness was, of course, impossible. The permissible variations 
from perfect straightness were purely a matter of judgment. 
Inasmuch as the blade was flexible, was of variable thick- 
ness, and curved both lengthwise and transversely, it had 
not been practicable to design a satisfactory gage, or other 
checking instrument. It should be said, by the way, that the 
purchaser's chief inspector was very competent, reasonable, 
and fair minded. The working inspectors under his super- 
vision were unusually well controlled. He had personally 
examined several blades and rejected the lot of several 
thousand. On the manufacturer's side, however, the same 



56 THE CONTROL OF QUALITY 

blades had been passed by a carefully trained corps of in- 
spectors who were in the factory's employ. Their foreman 
had reinspected a quantity of these blades, and passed 
them all. 

Here was a large plant running under pressure for pro- 
duction, with several days output stalled in the middle of 
the road because the purchaser said the work was wrong, 
while the maker insisted that it was right. The purchaser, 
of course, held the whip-hand, and it was of no avail to plead 
that there was little military or other practical advantage in 
such a degree of straightness as was required for these 
blades. The problem was one of finding the quickest way 
out of an embarrassing impasse. 

The cure for the difficulty, however, was simple. The 
purchaser's inspector was told that the, factory manage- 
ment felt the standard had been stiffened by imperceptible 
increments until it had become impracticable. It was re- 
quested therefore that he examine 20 blades which were 
presented for his inspection, and designate those that he 
considered straight. 

The 20 blades in question were obtained in this way — 
each of five of the company's best blade inspectors were 
asked to select, from the rejected lot, 10 blades that he knew 
were straight and 10 that he felt equally sure were not quite 
straight. In this way there were then accumulated 50 
"straight" blades and 50 "crooked" ones. A committee 
consisting of three of the factory inspection department's 
expert supervisors then agreed upon 10 blades from each 
lot of 50, and marked them accordingly with secret marks, 
10 as "straight" and 10 as "crooked." 

The result was that the purchaser's chief inspector 
passed 19 of the blades and rejected the twentieth for a 
surface defect not in any way connected with straightness. 
Of course, he was promptly told the whole story, and in a 



THE TYPES OF INSPECTION 57 

fine spirit of fair play he immediately ordered the entire lot 
inspected and accepted nearly all. 

This episode is related here because it exemplifies so clearly 
a number of inspection phenomena of the sort that must be 
taken account of, in determining what is to be avoided. 

Unnecessary Inspection 

Another thing which requires attention is the elimina- 
tion of unnecessary inspection. Many operations require 
no inspection whatever, or else the inspection of work after 
a given operation may cover also the work of several preced- 
ing operations. Similarly, and especially in the case of 
floor-inspection, if the first several parts inspected are found 
to be right, the inspection of the rest of the lot may be 
waived. The procedure is safer, however, if a few of the 
last parts made are inspected in the same way. 

Other parts may be of such minor importance and 
slight cost as to make it advisable to drop the inspection in 
favor of the more certain test of their use in the assembling 
department. This is true of most small screws and similar 
minor screw machine products. 

The Percentage of Inspection 

As to the quantity or amount of inspection that should 
be used and when it is to be applied, a safe general rule is 
this: Use 100 per cent inspection (i.e., the inspection of 
every piece in a lot as regards all essential qualities of the 
standard) when the work done largely affects other work 
that is to follow, as in the case of drawings, tool-room out- 
put, gages, etc., or when any part may unduly affect the 
integrity of the entire assembly. Furthermore, apply 100 
per cent inspection at points where an operation is subject to 
serious errors, or when one operation may control or mark- 
edly influence many subsequent operations. 



58 



THE CONTROL OF QUALITY 




THE TYPES OF INSPECTION 59 

Sampling — The Theory 

If less than ioo per cent inspection is used, we are 
brought to the consideration of sampling. For the most 
part, inspection is made possible economically by applying 
the theory of this method. This involves the assumption 
that a piece selected at random probably is representative 
of the rest of the lot, or that a portion of a quantity of some 
substance probably is like the remainder. The word 
"probably" here is to be noted. It is sound theory to as- 
sume that if something happens under given conditions, 
exactly the same thing always will happen again under the 
identical conditions, which is one way of stating the law of 
similarity in nature. In manufacturing, however, we are 
not dealing with a theory, but rather with a very practical 
condition of things, which is changing and varying all the 
time. 

Every portion of an ingot of metal, for example, differs 
from every other portion. This is so well recognized in the 
inspection of raw materials that very exact practices have 
been evolved for taking samples or " drillings " of metals 
for analysis; also for selecting samples of coal and similar 
substances. 

No such definite practice is practicable for sampling in 
shop inspection. The best we can do is to assume, in the 
case of first-part inspection, that if the first part made, after 
the tools are set up, is satisfactory, the following parts 
probably will be right; or to assume likewise that one part, 
taken at random from a lot of the same parts, probably will 
exemplify the condition of all of them. This, however, is 
not necessarily true. We should remember that one of the 
most common fallacies of reasoning, well known to students 
of logic, is that of arguing from a special case to a general 
conclusion. 

In sampling, this fallacy takes a peculiar form. You 



60 THE CONTROL OF QUALITY 

may say to yourself, for example, "This bolt which I hold in 
my hand, is well and correctly made. Therefore all the 
bolts in the box from which I took this one are correct." 
If, on the other hand, it happens that the bolt is not correct, 
you are not nearly so willing or quick to conclude that all 
the bolts are not correct, so you select one or two more from 
the box; and if they are correct, you promptly assume, as at 
first, that all the rest are correct, although you are not quite 
so certain. 

Such optimism may perhaps show a commendable spirit, 
but the plain fact remains that your conclusion may not be 
true, although it probably is. It is usually well to give 
everyone and • everything the benefit of the doubt. It 
might be said when a conclusion based upon sampling is not 
true, that the case in hand is exceptional and that "the 
exception proves the rule," but the inference is wrong. 
This is a very old expression in which the word "proves" is 
used in its original sense, as in proving a gun. In reality the 
exceptional case tests the rule. 

Safeguards for Sampling 

The use of sampling, especially in important and costly 
work, must be surrounded and reinforced with certain in- 
dependent safeguards. This makes possible the great 
economy which sampling permits, while protecting the 
conclusions from most of the probable errors, provided hasty 
deductions are avoided. 

Among such safeguards are the following : 

1. Mention has been made of the desirability of having 
the first and last few parts from each machine set-up checked 
by the tool-setter or taken to the inspector for checking. 
This can be extended by a continuous, random floor-inspec- 
tion or patrolling supervision. 

2. Parts may be taken at random from current product 



THE TYPES OF INSPECTION 6l 

and tried by actual assembly, thus discounting the danger 
due to the wait in shops and in component stores. 

3. Parts in stores may be similarly checked at random 
from time to time. 

4. The two-bin principle should be applied wherever 
work is piled up, either in process, or in stores, in order to 
insure an uninterrupted flow of work. (See Chapter VIII.) 

5. A sort of blind, double inspection can be tried oc- 
casionally, in order to check a doubtful inspection point, by 
sending the same parts through the same inspector twice 
without notifying the inspector. The practice often gives 
a valuable insight as to what is really going on. 

6. Each day a good part and a reject may be collected at 
random at each inspection point and carried to the central 
gage-checking point for independent verifying. 

7. One or two pieces may be quickly routed through all 
operations, being carried from machine to machine by the 
foreman inspector so as to discount the delays between 
operations. As each operation requires, roughly, a day for 
a lot of parts to pass it, a part requiring fifty operations will 
ordinarily take fifty days to pass through the shop. A 
"quick routed test part" or "pilot part," which can be put 
through in a day, will be found an excellent device for 
detecting trouble under certain circumstances. 

Other Economies in Inspection 

The cost of inspection may be reduced in a direct way by 
combining it with other duties, but any work so added to 
the duties of the inspector should preferably be of the sort 
that is best separated from actual production. The excep- 
tion is in the case of a combination of inspecting and re- 
pairing, as referred to earlier in this chapter. 

It is not unusual to have the inspector certify as to the 
amount of work done by each workman whose work he 



62 THE CONTROL OF QUALITY 

inspects. It is believed that this combination of duties 
should be more extensively used, especially in steel construc- 
tion and similar large outside work. The employment of 
higher grade men for both purposes is permitted by the 
combination of duties. 

In a highly developed central-inspection system the 
counting of work done is handled by the inspector as a 
matter of course. In addition, the collection of useful in- 
formation, the custody of work in process, dispatching the 
same, and otherwise assisting the shop, are all things in- 
spection is specially suited to take charge of. Other serv- 
ices, more indirect, which may be allocated to the inspec- 
tion department with profit will be mentioned later on. 



CHAPTER V 

THE INSPECTION DEPARTMENT IN THE 
ORGANIZATION 

Vital Importance of Inspection 

Effective use of inspection necessarily is predicated upon 
its recognition and elevation to a point where it is a real 
factor in management. 

The importance of inspection should be recognized in a 
practical and concrete way by assigning to it a place in the 
organization commensurate with the vital duty of safe- 
guarding the quality of the product, whatever that may 
happen to be. When this has been done it is possible to 
give quality the attention it deserves. For it seems beyond 
question that the most prominent feature in the progress of 
factory practice in the future should be the greater and 
more general appreciation of the possibilities of quality con- 
trol, the development of refinements in its application, and 
the consequent attainment of both higher standards of 
quality and greater fidelity to such standards, with a de- 
cided gain in economy. 

The last few years have witnessed the evolution of a 
science of management and its translation into an engineer- 
ing practice covering planning in its widest sense, the deter- 
mination of standards of output, and the methods of 
handling a complexity of human relations, rapidly changing 
under the reaction of labor to the new situations introduced 
into industry. The machinery thus created and developed 
will now be used to accelerate the progress of industrial 
management, with care for quality more and more as the 
guiding principle. It is but in the natural course of events 

63 



64 THE CONTROL OF QUALITY 

that the greater mechanical accuracy made more generally 
possible through development under stress of war time, to- 
gether with the experience of manufacturers during that 
period, will now result in an intensive application of these 
new forces in the betterment of the work of the industrial 
world. The reaction on labor alone will be worth the 
effort. As stated, this attitude on the part of managers leads 
toward better inspection, which in turn will have to be pre- 
ceded by a deeper understanding of the inspection function. 
Every student of industrial management must recognize 
that the late Dr. Frederick W. Taylor made a remarkably 
clear and powerful analysis of the elements of manufactur- 
ing, although he may not entirely accept the Taylor methods 
for handling the elements thus disclosed. It is therefore 
interesting to note that Dr. Taylor's analysis of the duties 
of foremen, even in ordinary machine shop practice, resulted 
in the separating out of inspection, as a function calling for 
an independent foreman. In other words, he recognized 
the necessity for an inspector or quality boss, just as he pro- 
vided for a "speed boss" to look out for quantity, and a 
planner to do the thinking and prearranging necessary to 
co-ordinate subsequent effort. This analysis is evidence of 
a realization that someone should attend to inspection, and 
that so important a duty is best carried out independently 
and therefore with authority. 

The Engineering Department 

Suppose that we analyze some great manufacturing 
enterprise into its most general terms. Our problem is to 
make, let us say, a large number of engines, or motors, or 
guns, or other articles assembled from component parts 
which must be made to rather definite standards of accuracy 
and finish. What the industry happens to be makes little 
difference, because all involve the application of labor to an 



INSPECTION DEPARTMENT IN ORGANIZATION 



65 




66 THE CONTROL OF QUALITY 

assemblage of raw materials. Perhaps the first large duty 
or group of duties that we would segregate in our minds 
would be the engineering group, whose duty is to make plans 
for something that is to be done in the future, and to con- 
centrate on the practical and intensive application of an- 
ticipatory imagination. 

This work is warranted because it reduces the cost of 
production through describing exactly what is to be done 
and thus avoiding waste of effort on the shop's part in doing 
things that are not wanted. This passion for visualizing 
work before it is performed and preparing plans showing 
what should be done, is resulting in the transfer of more and 
more work from the domain of "trial and error" in the 
actual fabrication of the work, to its more scientific treat- 
ment in the engineering department. All doubtful ques- 
tions are settled as a part of preparation for production and 
before the latter begins, and a sharp line is drawn between 
.experimental or research work and the business of making 
things. Vexatious and costly delays are confined to the 
laboratory and the engineering office in order that produc- 
tion may flow on without interruption from such things. 

Thus the designing engineer works out his plans on paper, 
describing in great detail what the shops are to make; the 
production engineer makes plans on paper covering the 
things to be done to obtain greater productive efficiency, 
and so on. None of this effort is expended in doing the 
physical work of production, but it does result in a much 
greater output from the whole organization. It pays 
amazingly. It is cheaper to correct mistakes on paper 
before they have been worked into steel. 

The Production Department 

Continuing the analysis of manufacturing, probably the 
next great function that will attract attention, if our minds 



INSPECTION DEPARTMENT IN ORGANIZATION 67 

are proceeding in an orderly manner, is that of production, 
which has the duty of applying human effort to the execu- 
tion of the plans made by the engineering group. The 
latter' s work is now subjected to the acid test — it is con- 
vertible into action, or it is not. 

The time element, it may be noted, is significant here, 
for production is most seriously engaged with meeting the 
pressing necessities of the present, j 11st as engineering deals 
principally with the future. Production solves its problems 
as it meets them in the actual physical performance of man- 
ufacturing, while the machinery is running — engineering 
solves just as many problems as it can mentally visualize 
and work out on paper before any wheels are turned. 

The Inspection Department 

It would seem that the next logical step in this process 
of analysis must reveal inspection, which has the duty of 
passing upon the results of production after the latter has 
endeavored to carry out the plans of engineering. Inspec- 
tion work is retrospective. It is performed after work has 
been done. 

Each of these three main groups of functions calls for 
special experience and for its own characteristic and pecul- 
iar attitude of mind. Engineering and inspection are the 
primary contributories of production, while all other fac- 
tory activities are secondary in the sense of being merely 
general service duties. 

A Parallel with Governmental Organization 

It is not difficult to find a parallel case in a field of admin- 
istration much older and wider than the industrial organiza- 
tion. The experience of men in evolving governments for 
social administration has developed the necessity for 
three main functions, which assure stability through mutual 



68 THE CONTROL OF QUALITY 

independence of authority in action, but with interdepend- 
ence and mutual helpfulness through balancing each other, 
just as there must be three points of support for stable 
equilibrium. The three governmental functions referred to 
are, of course, the legislative, executive, and judicial. It is 
easy to trace their correspondence with engineering, pro- 
duction, and inspection, respectively, which have the same 
general relationships. Inspection is judicial because it is 
measurement plus judgment. If it were easy to distinguish 
between the right and the wrong execution of either laws or 
plans, there would be little need of applying independent 
judgment, but in very many cases it is not easy. In the one 
as in the other, in the factory as in civil procedure, the best 
results demand for their attainment that the final applica- 
tion of judgment be made with authority subordinate only 
to the supreme controller of all three functions. 

Inspection's Relation to Engineering and Production 

If there is any one thing that the management of a large 
industrial enterprise needs in its business, it is the unvar- 
nished truth about what is really going on in the plant — not 
the reports from an espionage system, but the plain facts 
brought frankly into the open as to where errors are most fre- 
quently made, the extent to which they occur, and the causes 
of production choke-points. It is just as useful to know in 
detail what has been done as the work proceeds, as it is to 
know what you are going to try to do before you begin. If 
an engineer-executive has the facts he usually can cure the 
trouble. Yet ordinarily this information is the hardest to 
obtain, either promptly or accurately. The chance of get- 
ting it is much better, and under good management it is 
assured, if there is competent personnel in an unbiased 
position to observe, locate, and report the difficulties as they 
appear. This is a duty that the inspection department is 



INSPECTION DEPARTMENT IN ORGANIZATION 69 

best able to perform by reason of its freedom from respon- 
sibility for anything except passing upon quality. Here is 
another reason why the inspection department should be 
subordinate only to the management. There is a great 
value in having inspection in what might be termed, to fol- 
low the above analogy, a judicial position; but that value is 
seriously abridged if inspection is subordinate to either the 
engineering department or the production department. 

Failure to obtain both the standard of quality and the 
scheduled output will occur from faulty engineering or from 
a failure of the production department to carry out properly 
the engineering plans. If inspection is subordinate to en- 
gineering, the faults of engineering will not come to light 
when they should. That is only human — -but it is not 
scientific. Worse still, if inspection is subordinate to pro- 
duction, not only the latter's faults will be concealed but 
also there will be a strong tendency to skimp quality. 
When once quality is allowed to slip, costly losses will soon 
result in fact, although frequently not detected. 

Purpose Help — Not Mere Criticism 

When, however, inspection is raised to its proper posi- 
tion and is assigned the important duty of bringing the 
facts to the surface, it should be clearly shown to the other 
departments that the purpose is one of mutual helpfulness 
and service, and not one of destructive criticism. Facts 
are necessary to solve problems. If they are presented in a 
spirit of helping to conquer difficulties, surely no one can 
take offense. 

Quality is a variable. Everyone makes mistakes. It is 
immaterial who is to blame for them. It is folly to be forever 
in search of a "goat" when things go wrong; the precious 
time thus spent should be used more constructively. It is 
essential merely that the mistakes be promptly located, 



■JO THE CONTROL OF QUALITY 

recognized, and cured before loss piles up. The group of 
workers in the best position to do this are those in the least 
prejudiced situation and hence best able to see things as 
they really are. There can be but one conclusion, namely 
that the inspection department should perform this service. 
But it cannot do that efficiently if its hands are tied. 

The Real versus the Apparent Organization 

In the majority of factories, especially before the war, 
factory inspection received little recognition. Even now, 
in very few factories indeed is it given a chance to demon- 
strate its greatest possibilities for service. In nearly all 
plants, however, even those which are comparatively small, 
the latent possibilities of inspection can be developed if the 
real organization is made more nearly like the apparent 
organization. The difference between the two is often 
considerable. 

What maybe termed the "apparent" organization is that 
shown by the assignment of duties in the form of an organi- 
zation chart, or perhaps by the titles given to the various 
department heads and their assistants. Often, however, 
the actual work is not carried out in accordance with the 
apparent organization. Certain individuals will be found 
to be exerting a far greater influence than their assigned 
positions would seem to indicate. If the organization 
chart were redrawn to show the true way in which duties are 
carried out rather than how they are assigned in theory, and 
to indicate clearly a relationship between individuals in 
accordance with their proportionate contribution to the 
enterprise, then it would indicate the real organization. 

If an organization is analyzed with this test in mind, the 
discovery will probably be made that the inspection depart- 
ment's contribution is greater than the apparent organiza- 
tion would seem to indicate. If it is exalted to a position 



INSPECTION DEPARTMENT IN ORGANIZATION 



71 




72 THE CONTROL OF QUALITY 

equal to that of production and engineering, it will give 
a still greater return. If it is subordinated, its greatest 
potentialities will be lost. 

Engineering and Inspection 

As has been stated elsewhere, the working or practical 
standards of quality are furnished in the main by the en- 
gineering department. These standards serve well enough 
for work that is plainly seen to be well inside the limits or 
well outside the limits. The difficulty in fixing standards of 
quality accurately arises from the large proportion of work 
which falls close to the limits. 

At this point the engineering department must be re- 
leased in favor of the inspection department, for in such 
cases, in the last analysis, someone must make up his mind 
as to whether the work should be passed or rejected. Thus 
the element of personal judgment enters, and a specialized 
technique must be cultivated and applied. For judgment 
varies as between individuals, and in the same individual at 
different times. To this fact may be ascribed many of the 
phenomena of the inspection of close work, where only a 
small percentage of parts are made that cannot be rejected 
on some technicality. This is the case with respect to di- 
mension, and still more with respect to matters of finish, 
because judgment is accentuated so much more in inspect- 
ing for finish. Now the value of judgment depends upon 
its freedom from influence. 

Production and Inspection 

The inspection department's relation to the whole or- 
ganization is judicial rather than creative. It is responsible 
to the management for detecting failures in quality, and in 
that sense it bears a very heavy responsibility for the main- 
tenance of standards. It does not manufacture, however, 



INSPECTION DEPARTMENT IN ORGANIZATION 73 

and therefore when poor work is produced the production 
department cannot usually shift the blame to the inspection 
department. The production department should be made 
to realize that it is itself responsible for the quality of its 
product — it makes the work right or it makes it wrong. If 
the production force is organized by operations, the in- 
dividual subforeman, tool-setter, or adjuster in charge of 
each operation should be made to feel that he is responsible 
for the quality of the work produced under his direction. 
In addition to checking the work frequently in person, he 
may be required to bring the first two or three pieces made 
after each new machine set-up to the inspector for verifying, 
but merely as a guide in his own work. Both departments 
then bear a definite responsibility to the management for 
quality, but independently and in different ways. 

It is a well-accepted principle that responsibility should 
be re-enforced by adequate authority. Accordingly, if in- 
spection is charged with the responsibility of stopping losses 
from work not up to standard, it must be given the authority 
to stop machines. When this authority is granted, it is 
only good judgment to specify an exact procedure for advis- 
ing the responsible production executive, also for putting 
the machine back into production. It hardly need be added 
that such authority is not likely to be used if the inspection 
department's freedom is restricted by its subordination to 
production. 

In fact, if inspection is to develop its greatest possibilities 
for service, it requires room to work and a free, fair chance 
to solve its problems. If you believe in inspection suffi- 
ciently to have an inspection department, why not give it 
a chance to show what it can do ? 



CHAPTER VI 

INSPECTION'S CONTRIBUTION TO GENERAL 
SERVICE 

The Collection of Useful Information 

One of the greatest benefits of the inspection service 
comes from its power to bring promptly to the attention of 
the management information as to the true state of affairs 
in the shops. No tool is so useful to the manager as knowl- 
edge of the facts, yet nothing is so hard to obtain. The 
foreman-inspector of each shop is very close to what is going 
on in that shop, and is likely to be in the most unbiased 
state of mind because he is an observer rather than a 
producer. 

Counting the work done and certifying to it is part of 
the inspector's duty as a matter of course. Summarizing 
this information for reports to be used for the purposes of 
the pay-roll, the cost records, and the production records 
may or may not be a part of his duty, depending on the 
character of the work. If this warrants a well-developed 
inspection system, it is quite likely that the foreman-in- 
spector of every sizable department will require clerical 
assistance. If so, this clerk may just as well assemble the 
count of work performed in his department, before it is 
transmitted to the general factory offices. When produc- 
tion and cost data are assembled and analyzed by the use of 
power-driven tabulating machines, the data may be 
collected at the original sources and its accuracy certified 
to by the inspectors, with the obvious advantage of securing 
competent assistance in gathering the information together 
with the resultant saving in clerical expense. The addi- 

74 



INSPECTION'S CONTRIBUTION TO SERVICE 75 

tional burden on the inspector is slight, and the added duty 
may even be beneficial because it tends to bring him closer 
to his job. 

There is another sort of information of equal or of even 
greater importance, which the inspector evidently is in the 
best position to obtain; namely, the location of production 
troubles, the isolation of their causes, and frequently the 
offering of suggestions for their cure. Production difficulties 
ordinarily appear in the form of too great losses in spoilage, 
or through the slowing down of production at some opera- 
tion, thus creating a choke-point or a partial choke-point. 
It is essential, of course, to correct the difficulty as soon as 
possible, but to do this it is necessary to develop and bring 
to light the true causes. 

Trouble Reports 

A very useful device for the prompt collection of such 
data may be secured by providing a printed form of 
''trouble report" to be made out and sent by foremen- 
inspectors of shops to the chief inspector, who will transmit 
such facts as seem worth attention to the department that 
should correct the trouble — the management being fur- 
nished with a copy. The trouble report should read pref- 
erably as shown in Figure 13. 

A detailed list of usual soruces of trouble, such as tools, 
gages, material, and so on, may be added for convenience, 
but the essential idea is to make the foreman-inspector feel 
the responsibility for promptly reporting the facts and 
nothing but the facts. Hence the requirement that he 
must state either that he "knows" or that he merely 
"thinks" that the trouble is due to the cause stated in his 
report. For the trouble report to be used successfully, the 
foreman-inspector must have confidence in the judgment, 
fairness, and courage of his chief — -he must feel sure that he 



76 THE CONTROL OF QUALITY 



From Foreman- Inspector 

To Chief Inspector 

Shop Date 

Operation Hour 

I report the following trouble 

I know think (scratch out one) that the trouble is due to the following 
cause 



Figure 13. Trouble Report 

will be backed up if he is right. Further, the management 
should make quite clear that it is looking for facts in order 
to cure troubles, and not to find someone to blame. There 
is no surer way to put a premium on the concealment of 
facts than by trying to fix the blame on an individual, nor 
does blaming someone help to cure the trouble. Presum- 
ably each executive holds his job because he is the best 
available man for the position. If he is not, the manage- 
ment will know it much sooner if he and his associates are 
not continually placed in the position of being called upon 
to make excuses. 

The Inspector's Sense of Responsibility 

Certain phases of the psychology involved in trouble 
reports deserve more detailed consideration at this point. 
In the first place, if the device of the trouble report is to be 
successfully applied the inspector must be made to feel that 



INSPECTION'S CONTRIBUTION TO SERVICE 77 

he is exercising a trust, and that the management reposes 
unusual confidence in his impartiality and adherence to 
accuracy. This feeling on his part has two very practical 
results: first, the information will be more truthful; second, 
the inspector will perform his other duties with the increased 
efficiency that flows from a stronger realization of his value 
to the organization. There are very few men who will 
not rise, in spirit as well as in- act, to meet increased 
responsibilities. 

At the same time the inspector should be made to know 
positively that accuracy will be insisted on. The latter 
purpose is accomplished by requiring him to state in each 
report whether he knows what he is talking about, or merely 
thinks the situation is thus and so. Quite a distinction is 
involved, of course, both in the report itself, as well as in the 
action likely to be taken. On the other hand, provided the 
inspector truthfully states the degree of his belief as to the 
facts, it is of comparatively little importance which form 
the report takes. 

A Typical Instance 

Experience with the trouble report as used in a very 
large and highly organized inspection department developed 
some very interesting reactions. This form of report was 
designed to meet a special set of conditions, first, because it 
was vitally important to get the best available information 
about a complex manufacturing situation as soon as pos- 
sible; and second, because stiffening up the morale was 
judged to be the most important thing in reorganizing this 
particular inspection department. A few days after the 
form of report was placed in the hands of the foremen- 
inspectors, reports began to come in without either verb 
"know" or "think" scratched out. That was to be ex- 
pected, as the inspection force had been led to feel that its 



78 THE CONTROL OF QUALITY 

work might be performed negligently or otherwise without 
visible effect on the running of the plant. All such indefi- 
nite reports, however, were returned promptly with the re- 
quest that they be corrected in this respect. The inference 
was clear that the reports were considered of value and were 
to be used. Some of those which had been returned never 
came back, as was hoped, and the total number of reports 
became less. But over go per cent of those which did come 
in read "I know." This is the thing to note especially. 
When the management began to take action on the more 
important reports, the inspectors' growing feeling of re- 
sponsibility was confirmed by seeing things begin to happen, 
and the. effect on the morale of the entire department was 
very marked. 

Reception of Trouble Reports 

As stated at first, the use of such reports carries with it 
the necessity of using them in the spirit in which all scien- 
tifically trained minds should work. They should be 
received as being presented in a spirit of helpful and con- 
structive criticism and as the opinion of an impartial ob- 
server reporting things as he views them. The department 
whose work is most involved must be made to feel that this 
is the way the report is offered, and to accept it in the same 
spirit. If the report is not well founded, no one is reflected 
upon so much as the inspector. If the report is correct no 
one should be so glad to discover, and to correct the trouble 
as the department responsible for the trouble. To secure 
this co-ordination and, in fact, to require a spirit of mutual 
confidence and good-fellowship, is distinctly the duty of the 
management. This is apparently a small point, but it is 
vital. 

The use of some such report will yield just as valuable 
returns in many other kinds of work than factory inspection 



INSPECTION'S CONTRIBUTION TO SERVICE 79 

in its more limited sense. Figure 14 is an example of a 
form adapted to use in a great ship assembling plant. 1 

Inspection and the Assembling Department 

After the various component parts have passed inspec- 
tion in the respective parts-making shops and have been 
placed in the finished-parts stores prior to being issued to 
the assembling department, it may be assumed with reason- 
able assurance that they can be assembled satisfactorily. 
There is an ever-present tendency, however, for work to slip 
away from the desired standards of quality, and to do so by 
such small daily increments that the changes are difficult of 
detection. Measuring devices, whether gages or precision 
instruments of more general type, and cutting tools, are 
subject to wear like everything else. The fact that the 
wear does not take place rapidly or evenly makes the 
process all the more subtle and insidious. Then there is al- 
ways the chance of a gage being accidentally injured, and 
work incorrectly disposed of, in consequence. In close 
work, as already noted, these troubles are accentuated by 
personal errors and by a multitude of other influences. 

The net effect is, that in spite of every reasonable precau- 
tion quality will slip, and the errors may not be detected 
until the parts are issued for assembling. If the errors are 
due to gradual wear or similar cause, the condition will be 
manifested first by a slowly increasing difficulty in assem- 
bling, which is more dangerous than an absolute failure to 
assemble. For example, a part may assemble satisfactorily, 
and even pass final tests in the assembled mechanism, and 
still be just enough outside the lowest permissible limits to 
wear into a non-functioning shape after a short time in ac- 
tual service. 



1 Furnished through the courtesy of William B. Ferguson, formerly Assistant to the President 
and Manager of the Division of Standards, American International Shipbuilding Corporation 
(Hog Island). 



8o 



THE CONTROL OF QUALITY 



HULL NO. _ 
REPORT NO.. 
DETAIL NO. 



From Way No._ 
Agreement No. 



Agreement Name_ 



Location of Work_ 



1 Faulty Material? 



Faulty Workmanship? 



2 Had work been completed on ways 



3 Could fault have been caught by more careful inspection?. 

4 In your opinion should work have been passed on ways? 

5 To whom should this be reported so that it will not 
occur again 



Job Finished 



No. of men on job_ 



_No. of man hours_ 



Description of Fault 



Figure 14. Inspection Form — American International Corporation, Hog 

Island 



INSPECTION'S CONTRIBUTION TO SERVICE 8l 

There was a particular make of engine of excellent and 
even very advanced design, which nevertheless failed in 
certain cases, most unexpectedly, after being used for a 
short time. A cursory viewing of the factory's inadequately 
controlled inspection system revealed an obvious reason for 
the service troubles which were killing future business. 
Parts of the mechanism of the engine in question required 
very accurate work. Some of these parts, with proper in- 
spection lacking, were found to be just good enough to pass 
factory tests, but not good enough to stand up long in ac- 
tual use. 

Benefits to Entire Factory 

With a highly organized inspection service in the shops 
and extending into the subassembly and final assembly 
rooms, a means is provided for avoiding such difficulties. 
The direct work of inspecting in the assembling department 
is often of less value, however, than the collection of infor- 
mation of value to the rest of the factory. The assembling 
rooms are a particularly fertile field for revealing errors, and 
the inspection department, for the reasons previously stated, 
is specially in a position to catch these errors and to pass the 
word about them back into the factory for the help and 
guidance of all. Time is a vital factor in such matters, and 
a well-organized inspection service will be able to send the 
warning back along the line with the proper speed. The 
possibilities of such a service are so great that it may be the 
part of wisdom to place the assembling under the general 
control of the head of the inspection department, especially 
if such a combination of duties will serve as a further reason 
for selecting a man of larger caliber for that important 
position. 

Curiously enough, if the work is not strictly inter- 
changeable there is often a greater reason for increasing the 

6 



82 THE CONTROL OF QUALITY 

importance of the inspector's position in the assembling 
department. In this case, of course, selection of parts be- 
comes necessary. Very often it can and should be made a 
separate operation from that of putting the parts together. 
The work of choosing parts that will mate properly in- 
volves measuring the parts and then sorting them out in a 
systematic manner into a few groups, each of which is made 
up of parts of very nearly the same dimension. The proc- 
ess is simpler if the work is of a character to warrant the 
use of selective gaging. It is merely an extension of division 
of labor to separate this work of sorting from that of as- 
sembling, and the sorting is more closely allied to inspection 
than it is to production. 

An Example of Selective Assembly 

An example of this kind is to be found in the manufac- 
ture of rifles or pistols which have raised sight-bases integral 
with the barrel. The barrel has a milled thread which 
screws into a similarly threaded opening in the receiver or 
frame. The barrel must screw into the frame so that the 
sight-bases are in line with the vertical plane of the frame 
(to insure correct alignment of the sights) ; and, in addition, 
the barrel and receiver must be drawn together at a given 
tension, this "draw" being required to be between given 
limits expressed in pounds for a stated lever arm or length of 
wrench. Both barrel and frame require many operations 
before they are ready for assembling, and several of these 
operations are referred back to the location of the milled 
threads and sight-bases. Needless to say, it is not always 
the simplest matter in the world so to locate and mill the 
threads as to fulfil the two conditions of sight alignment and 
draw of threaded joint, while still conforming to full inter- 
changeability. Therefore, if a proportion of the parts de- 
mand selective assembling, a very considerable amount of 



INSPECTION'S CONTRIBUTION TO SERVICE 83 

work can be saved if the parts are separately gaged, with 
gages provided with, say, 10 numbered stages, to indicate 
corresponding positions in relation to the draw marks when 
the gages are set up with a fixed turning moment of, say, 
n pounds at the end of a wrench a inches long. The female 
gage applied to the barrel and the male gage applied to the 
frame are so calibrated that barrels drawing to point 8 on 
the barrel-gage, for example, will properly mate with frames 
drawing to point 8 on the frame-gage, and so on; and the 
parts will be sorted accordingly before issuing to the as- 
semblers. 

This method may be applied in principle to many cases 
in which economy in making the parts indicates the desir- 
ability of selective assembly. It will be noted that what 
really happens is that by means of the inspection and sorting 
of parts the assembling advantages of true interchangeabil- 
ity are secured. 

The Custody of Work in Process 

Many factories possessing very complete systems for 
production control are more concerned with the paper 
records of the system than they are with the systematic and 
orderly arrangement of the work in process of manufacture 
in the shops. The machinery may very likely be arranged 
to secure the best possible compromise for straight-line 
routing. If the work is large in volume and concentrated on 
one product, the machines are arranged in the order of the 
operations, so that work flows from machine to machine in 
regular sequence. If the work is varied in character, the 
machines are arranged by classes, as lathes, planers, millers, 
and so forth. In either case it is likely that planning and 
routing are well cared for in any modern shop. It is a 
common fault, however, for the work in process to be piled 
all over the shop. Even if the work flows directly from 



84 THE CONTROL OF QUALITY 

machine to machine, it is no unusual sight to observe parts 
rusting at the bottom of a pile where they have lain for 
months, or other parts in like condition under an inspector's 
bench. 

The first point to be determined is whether this condition 
should be corrected. In certain instances, as in a great 
shipyard machine shop, the change may not be practicable. 
In most cases, however, it is worth while to make the effort; 
nor need it involve much expense, provided there is an 
effectively organized and managed inspection department to 
which this duty can be turned over. If central inspection is 
in use the job is readily taken care of. If not, the inspector 
at least can guide the work into a more orderly arrangement 
if he is given the authority to have work moved to the next 
machine after he has passed it. The placing of work 
naturally carries with it the custody of work in process. A 
little encouragement of the inspection department will 
develop a "fatherly" interest in the work itself, from which 
will flow a more orderly shop. 

Stimulus to Order and Cleanliness 

While considering the advantages obtained by a more 
systematic arrangement of the shop as regards work in proc- 
ess, the effect of order (and the greater shop cleanliness it 
permits) upon the working force should not be overlooked. 
An artist's temperament may be suited, perhaps, to doing 
good work under messy conditions, but the average man 
does better work if his environment is orderly and clean. 
It is well recognized that a desk covered with papers is not 
desirable. It has come to be regarded as an indication of a 
mind in the same condition as the desk. Does not the same 
criterion hold in the shop? 

The first step in securing order, if a reasonably good shop 
arrangement exists, is the prompt sorting out of work as it 



INSPECTION'S CONTRIBUTION TO SERVICE 85 

leaves the machine, followed, of course, by a systematic 
placing of the work after it has been sorted. 

The Analysis of Work in Process — "Good" and "Bad" 

Sorting out work in process by inspection requires the 
guidance of some sort of classification ; the matter cannot be 
dismissed by merely saying that work is good or bad. The 
parts or pieces of work that are passed by the inspector may 
be designated as "good parts" or "good work," as this ter- 
minology is brief, and the term "good work" is definite and 
accurate enough, provided we remember that the work is 
probably up to standard. As there is, of course, the men- 
tal reservation that the inspector may be wrong, there is a 
necessity for applying sampling tests to good parts from 
time to time, and for surrounding the inspector's work with 
safeguards, as set forth in Chapter IV. Parts obviously 
good require no other treatment than to be passed on to 
the next stage in their manufacture, assuming that some 
definite place is assigned for their temporary storage until 
the succeeding operation. 

"Rejected work," that is to say, "bad work," calls for 
analysis into several classes with appropriate definitions for 
each class. As in the case of good work, allowance must 
be made for the possibility of error on the inspector's part. 
Provision should be made so that work rejected on the first 
inspection may have some chance of reinspection. It is 
quite the usual thing in the inspection of all kinds of work, 
from shipbuilding to small interchangeable and high-grade 
parts, to have some of the rejected work really fit for passing. 

Handling Rejected Parts 

Next comes up the question of how the rejects should be 
handled — we are concerned principally with interchangeable 
parts because such work furnishes the widest range of ex- 



86 THE CONTROL OF QUAClTY 

amples illustrative of inspection. The first step is to sort 
out those which require only a remachining on the machine 
from which they just came. Usually too little metal has 
been removed, or further polishing is required, and the 
work can be made good by the shop itself. Ordinarily this 
work should be done by the machine operator who did the 
work in the first place, and on his own time. Of like nature 
are the instances of parts with certain operations missing; 
also those which are best repaired on jigs and fixtures avail- 
able only in the shops. 

The rejects remaining after taking out the "shop repairs" 
should be accumulated at some point in the shop, preferably 
in a space set aside as the shop salvage space and under the 
care of the inspection department. At this stage, when 
sufficient rejects are accumulated to warrant the work, a 
reinspection should be made, in which the parts are sepa- 
rated into two, or possibly three classes, as follows: 

I. Spoiled parts, which should be sent to the factory 
salvage room to be kept under lock and key ; for if this is not 
done, some of them, under stress for production, are apt to 
find their way back into process by some path or other. In 
the salvage department they will be carefully examined 
with a view to their conversion into the most marketable 
form, either as scrap or otherwise. Circumstances will indi- 
cate whether they should be mutilated to prevent their use 
except as scrap, or sold as they are for use in another article. 
Springs, for example, rejected as below your own standard of 
quality, may be sold to a consumer whose needs are less 
exacting. You can afford to supply him at a lower price 
than he would otherwise pay, and both of you make money. 
A cleverly handled salvage department, which classifies the 
scrap from a large factory in this way, and which is alertly 
in search of better markets for its goods, is a money-maker 
in itself. 



INSPECTION'S CONTRIBUTION TO SERVICE 87 

2. Rejected parts which require special work to bring 
them up to standard but which exist in sufficient quantity to 
warrant such repairs should be sent to a separate parts-re- 
pairing department or "hospital," specially designated as 
such, and located clear of the regular production depart- 
ments. This is the place for the all-round mechanic with a 
taste for improvising and inventing. Supply this little shop 
with a few general utility machines, welding outfits, and so 
on, and considerable loss will be avoided. Apply the most 
rigorous inspection both to its work during the repairs and 
to its output. 

In the course of repairing some parts, occasions may 
arise when it is necessary for the repair department to send 
the work out into the factory for some treatment or process 
beyond the repair shop capacity. If this occurs, by all 
means provide a special routing card of distinguishing color 
to go with the work, and return the work to the repair shop 
for inspection. Otherwise the repair shop inspector can- 
not be held responsible for the quality of repaired work of 
this character. In addition, he knows best what defects to 
look for by reason of his previous acquaintance with the 
parts in question. Finally, the repair department should 
keep a follow-up record of all of its work so sent out. 

It is suggested that very careful consideration be given 
to the matter of a separate repair shop for rejected parts. 
Too frequently the attempt is made to do such work, or a 
large part of it, in the parts-making shops. Then again, 
work is often scrapped that otherwise would have been re- 
stored to. a perfectly satisfactory condition in a special repair 
shop, whose working force is skilled in such things and proud 
of its ability to accomplish the apparently impossible. 

The effect on production of having repairs made in the 
local parts-making shops must also be considered. Such 
work calls for the more expert workmen, so that the repairs 



THE CONTROL OF QUALITY 



. HlB ■■■■ 


" > : ■: ■~*S ; * i . ^IB : -^ 




* 




"■ ■=•■-; 


V Jij^^lli^p. „~: ^^M 


Sr 


• ... :: , ; : :¥; :; ;1 : 






m 



u 



o 



INSPECTION'S CONTRIBUTION TO SERVICE 89 

cost not only the direct time of such men, but also the in- 
direct cost of lessened output due to their separation from 
the regular production work. 

One more reason for the separate repair shop: When 
a great number of parts are turned loose in a large and com- 
plexly equipped shop, strange and curious things happen. 
Some parts are likely to run wild unless their fields of move- 
ment are carefully restricted. If repair work is superim- 
posed on the routine production, some of the repairs are 
"quite capable of running in circles. They are inspected 
and repaired, and inspected again. The same individual 
pieces are returned for repairs and then inspected, and so on 
indefinitely, until they give way under the strain of so much 
activity — the best disposition of them because really the 
cheapest. "Circling" is of more frequent occurrence than 
might be imagined, because it is exceedingly difficult to 
detect, unless the work is of such a character that the in- 
spector stamps a mark on the work after each important 
inspection, and even stamping may not prove effective. 
The danger of circling, however, is obviated by rigorously 
excluding repair work from the parts-making shops. 

3. Under some conditions it may be compatible with 
business policy to consider a third class of rejected work. 
This case occurs when some of the rejected work is suitable 
for use in a second-grade product. Presumably such a 
product will not be marketed under the company label and 
the necessary precautions will be taken to insure the pro- 
tection of the reputation of the company's standard goods, 
as well as to insure that the manufacture of second-grade 
goods does not become the factory's principal occupation. 

Quality as an Incentive to Production 

With work classified by inspection as indicated above, it 
is no difficult matter to count the work of each class and 



90 THE CONTROL OF QUALITY 

tabulate the results. In this way the inspection force pro- 
vides the usual production data, as referred to in the preced- 
ing chapters. The same information in somewhat modified 
form is the basic matter for the all-important quality records. 

Certain of this information is of special interest to the 
individual workman, and may be used to great advantage 
in stimulating better workmanship and thereby greater pro- 
duction. In the first place, the output of good parts for the 
day, presented in simple form, may be posted on a shop 
bulletin board devoted to this purpose only. The results 
should be contrasted with the scheduled output desired, and 
to this may be added other significant information, such as 
the statement, for example, that "Operation No. 23 spoiled 
20 per cent of its pieces today. This is a difficult process, 
but we will have to hustle tomorrow to meet the schedule." 
Workmen are interested in this sort of thing, much more so 
than might be supposed. If they are not, the fact is ad- 
vance notice to the management to overhaul the things that 
affect the good-will of the so-called "human factor." 

Bulletin boards, it may be said, can be made much more 
useful as an instrument of publicity if attention is given to 
taking down notices as well as to posting them. The shop 
bulletin board is too often plastered with papers and notices 
of ancient vintage. Its effectiveness increases remarkably 
if it is kept absolutely cleared except when something is to 
be put across quickly. Then post your notice, briefly worded 
and clearly printed in large type, and just as soon as it has 
served its purpose, have it taken down, and the boards left 
clear as before. 

The Individual Worker's Interest 

Much of the data accumulated by the inspection depart- 
ment is of greater interest to individual workers than to the 
entire shop working force, considered collectively. Bill 



INSPECTION'S CONTRIBUTION TO SERVICE 9 1 

Jones's interest in his work can be stimulated very often by 
showing him the effect that his personal endeavors have had 
on the output of his shop. The inspection department's 
records will provide the excuse for Bill's production boss to 
discuss things with him in a friendly way. Good-fellowship 
is pretty sure to result and the chances are that both Bill 
and the factory will profit as he begins to react to this sort of 
encouragement. 

I should hesitate to stress this thought, in view of the 
feeling of some executives, if I had not seen the results in 
practice; for this is not theory, but hard fact. We talk a 
great deal about welfare work and carry some of it into effect 
with very desirable results, but what can be closer to the 
workman's interest than his regular work? You must 
answer for yourself whether the opportunities for building 
up the worker's interest in what he is doing are utilized to 
the full in the plant or plants in which you are personally 
interested. I do not refer to creating "bread-and-butter" 
interest — that is the usual appeal of incentives for stimulat- 
ing production — but rather to the pride of good workman- 
ship and the satisfaction of personal achievement which go 
to make up the worker's "professional pride." 

Interest in the Work Itself 

The modern industrial system, with its minute division 
of labor, has been freely criticized for reducing machine 
operators to mere automatons, forced to eke out an exist- 
ence of tedious and countless repetition of the same opera- 
tion. It is alleged that this endless repetition results in 
bodily, mental, and spiritual fatigue. The system of man- 
ufacture cannot be abandoned, because the division of labor 
results in too great an economy of effort even to think of its 
elimination. On the other hand, there is one simple but 
very effective corrective measure that we can apply, namely 



92 THE CONTROL OF QUALITY 

to encourage the operator's interest in, and to excite his 
curiosity about, the work he is engaged in doing. Now the 
theme that runs through this entire subject is that quality 
is variable, hence no two pieces turned out by any machine 
operation are alike. The points of difference may be com- 
paratively small, but to the eye of the trained expert these 
same differences grow to look much larger and to be very 
apparent and real. It is a question of relativity and of 
degree. 

Expert Knowledge — Causes and Results 

To the trained eye of an experienced inspector the in- 
terior of one rifle barrel is quite different from another, 
whereas the greatest difference you or I might note, after 
repeated trials, would be a slightly fuzzy spot resembling a 
pencil mark. The inspector would tell you that this barely 
distinguishable spot indicates a bad drill groove, but we 
should not be at all certain as to the degree of the defect, its 
location, or even its existence. In the course of time, how- 
ever, and with much repetition we could learn to distinguish 
these and similar defects or differences. Things that ap- 
peared indistinguishably small at first would become of 
appreciable size, and finally they would take on individual 
characteristics. But the main point I wish to bring out 
is that we should never know about them at all, if they 
were not first pointed out to us by someone skilled in their 
detection. 

Now, the same thing occurs with the average machine 
operator. He may drift along without noticing the results 
of his efforts except quantitatively. Especially is it likely 
that he will have very little idea of the fine points in the 
work which are subject to his control, nor of the things he is 
in a position to influence, nor why and how he can do so. 
It is no great trouble, however, for the inspector (or the 



INSPECTION'S CONTRIBUTION TO SERVICE 93 

production boss, if you prefer) to show him how each part 
differs a little from the next one ; also what different kinds of 
differences exist and what causes them, so that he can see 
for himself what he is doing qualitatively. Thus he will 
learn how his failure to clean off the chips, when bedding a 
piece, throws out his own work and perhaps the next man's, 
and almost certainly makes unnecessary work for the pol- 
isher. Or perhaps he will see that forcing the cutting tool 
causes him greater personal loss in total output than if he 
used less apparent speed. The net effect, however, will be 
the widening of his viewpoint, the building up of an interest 
in his work, and the consequent and proportionate lessening 
of fatigue. 

Interest in Quality versus Fatigue 

Many men can play golf every day in the week including 
Sunday. They seem to enjoy the repetition without expe- 
riencing unhealthy fatigue, and the discouraging monotony 
of their novitiate is forgotten. The same thing applies in 
principle in our daily work, no matter how restricted its 
field ; if it is interesting the resulting fatigue is a healthy one. 
But the work is only made interesting through an apprecia- 
tion of its fine points. It may take years of application to 
be able to see for ourselves those fine points and small dis- 
tinctions, or some more fortunate person may be kind 
enough to point them out to us early in the game. 

The modern application of division of labor has brought 
with it an acute problem due to extreme limitation of indi- 
vidual tasks, but the apparent smallness of the field of work 
covered by any one machine operator can be changed into 
one of much greater interest and wider scope by suggesting 
a different viewpoint to the workman. The employer 
might well consider carefully the mutual benefit to be de- 
rived from educating the worker in the finer points of his 



94 THE CONTROL OF QUALITY 

job, and from doing so in a spirit of friendly helpfulness that 
will build up a feeling of mutual interest in a common task. 
The workman usually is not capable of doing it alone, but 
he can be helped to do it by means of the regular factory 
organization if the employer will direct the foremen toward 
this different attitude in dealing with their men. 

A Phase of a Major Problem 

It is suggested that this is one way to help correct one 
of the major problems confronting engineers, which Herbert 
Hoover recently expressed in the following language : 2 

We have until recently greatly neglected the human factor that 
is so large an element in our very productivity. The development 
of vast repetition in the process of industry has divorced the em- 
ployer and his employees from the contact that carried responsibility 
for the human problem. 

I am daily impressed with the fact that there is but one way 
out, and that is to again re-establish through organized representa- 
tion that personal co-operation between emploj'er and employee in 
production that was a binding force when our industries were 
smaller of unit and of less specialization. 



2 From Mr. Hoover's presidential address to the American Institute of Mining and Metal- 
lurgical Engineers, Feb. 1920. 



CHAPTER VII 
INSPECTION'S RELATION TO PLANNING 

The Flow of Work in Process 

It is quite the usual thing in factory parlance to use the 
term "flow of work in process." More frequently it is ab- 
breviated to "the flow of work," or just "the flow." This 
little expression, which is used so readily and easily, covers a 
matter that is intimately interwoven with the whole fabric 
of manufacturing ; for the flow of work is of the very essence 
of production. 

Manufacturing results from the combination of labor, 
machinery, and material — remove one of the three and the 
process ceases. If we can keep the flow of the material 
under control, we are in a position to control manufacturing ; 
or, as has been said many times, "planning begins and ends 
with material." Thus one of the principal aims of planning 
is secured by arranging for a continuous supply of material 
to each production point, and at a velocity or rate of flow 
set to permit the scheduled output for that point. 

It would appear also that the economy of manufactur- 
ing is greatest when there is an even and uninterrupted flow 
of work all along the line throughout the factory. Uni- 
formity seems to be generally desirable in manufacturing. 
Let us consider some of the reasons for. this. In the first 
place, there is no advantage gained by pushing one opera- 
tion ahead of the average scheduled rate of production. 
The average rate at which completelyassembled mechanisms 
can be produced, and hence the average output of finished 
articles, is fixed by the average output of that component 
part which lags most in the manufacture. In fact, the rate 

95 



9 6 



THE CONTROL OF QUALITY 




INSPECTION'S RELATION TO PLANNING 97 

of total output is determined by the rate of flow of work 
through the single manufacturing operation or process that 
is lagging — "The speed of the fleet is the speed of the 
slowest ship." 

Uneven Flow — Disadvantages 

When assembling is permitted to proceed more rapidly 
than parts can be produced, it soon eats up the available 
reserve of parts and a famine results, with its accompanying 
pressure on the parts-producing shops. The first effect of 
too great pressure for quantity output is psychological — 
it amounts in practice to "getting everybody all worked 
up." The same thing happens when the train stops at an 
eating place — "twenty minutes for dinner — lots of time." 
All of us know what an iron nerve it takes not to hurry 
through with the job in half the time, at the expense of both 
appetite and digestion. When unusual pressure is placed 
on a shop the foremen stand over the men and hurry things 
along, with the net result of less output and of poorer qual- 
ity. When a factory is run in this manner the cost of in- 
spection for maintaining the set standards is much greater 
than it need be under more normal conditions. In the same 
way other indirect expenses are increased disproportion- 
ately. Thus transportation of work in process is much less 
expensive if carried on at a uniform rate, instead of being 
turned into the movement of many small lots of parts as 
soon as they are produced. 

The ideal plan is so to protect the flow of work as to have 
fixed or schedu^d quantities passing each production point 
during each unit of time. Unless we approximate to this 
ideal within reasonable limits, we shall have less production 
and at the expense of undue strain of the producers. When 
real emergencies occur they should find the organization 
fresh and ready to meet them. 



98 THE CONTROL OF QUALITY 

Effects on Piece Work 

Another serious defect resulting from an uneven flow of 
work arises from the fact that the continuous use of piece 
work is interfered with. Everyone knows that the output 
under a straight piece work or other system of payment 
based upon paying a man for what he does, is very much 
greater than when the man is paid for his time, on a day- 
wage basis. But the advantages of piece work cannot be 
fully realized unless there is a supply of material waiting at 
each machine for that particular operation. If there is a 
hitch in the chain of supply, workmen are soon to be seen 
standing round waiting for material to work on. It is not 
their fault, and they must be paid "day-work" for any 
appreciable loss of working time imposed upon them. 

Supply of Raw Materials 

Approaching the question from a different angle, we may 
note a similarity of situation in the supply of raw material. 
A prompt and continuous supply is always important, but 
during the war the procurement of material and supplies 
in the order and in the amounts required for continuous 
production assumed serious proportions. In the ship- 
building business especially, this matter of procurement 
took on a new value, and it is a safe statement that the 
speed of building in any yard was determined first and to 
a controlling degree by the efficiency of the preplanning for 
this purpose. 

Even if the size of a factory's raw material storehouses 
and storage spaces were not influenced by a desire to be able 
to take advantage of favorable market conditions, it still 
would be necessary to set aside the space. A stock must be 
accumulated against possible failures in delivery, in order 
that machines may not have to be shut down for lack of 
something to work upon. 



INSPECTION'S RELATION TO PLANNING 99 

Material in Process 

The identical principle applies to providing a supply or 
"bank" of material ahead of each manufacturing operation 
or production point, although this fact is not so generally 
appreciated. A proper flow of work can hardly be main- 
tained with less than a half-day's supply ahead of each 
operation, although the amount of work in each bank is 
governed by local conditions. It is understood that the 
French small-arms arsenals were eminently successful in 
obtaining large output of high quality under very trying 
conditions; also that it was the practice to keep at least a 
day's supply of work (and two days' if practicable) ahead of 
each operation. 

Breakdowns of equipment and other troubles are bound 
to develop choke-points from time to time, and an unbroken 
flow can only be insured by building up and maintaining 
reserves all along the line. These banks of material can 
then be drawn upon as needed to keep the machines going 
ahead of the choke-point, until the production point that is 
in trouble is restored to running condition. Then the re- 
serves can be again accumulated by extra shift work. 

From this point of view, there is a bank between the 
assembling room and the parts-making shops in the form of 
a finished component stores, which bears the same relation 
to the assembling department that the raw material stores 
bears to the parts-fabricating shops. 

The quantity of parts to be kept in each bank depends, 
of course, on the likelihood of trouble at preceding opera- 
tions, or other interruptions to production. For example, 
if it is probable that changes in design or method of manu- 
facture are to be made, it must be remembered that a change 
of any sort means a serious interruption in the flow of work. 
To handle the situation, when a change must be made, 
requires special treatment in each case, and calls for masterly 



IOO THE CONTROL OF QUALITY 

planning of the highest order. It is economy to take the 
time to do this planning before carrying out the change. 

Insuring a Continuous Flow 

The effect of a breakdown in production can be mini- 
mized at times by providing the factory with a chart show- 
ing approved alternative routings of the work. It is not 
safe, however, to route work more than two ways simul- 
taneously, especially if there are many parts in flow. Special 
care should be taken when two routes are used to keep dis- 
tinct the work sent over each route, and in this effort the 
inspection department can be of the greatest assistance. 

Similarly, the inspection department, in its regular task 
of sorting out the defective parts, makes a large contribu- 
tion to promoting a uniform flow of work, for it is essential 
from the standpoint of protecting the flow that rejected and 
condemned work be disposed of swiftly and promptly re- 
moved from the shop. 

The control of supplies of material and of banks of work 
in process, and therefore the control of the flow of work 
throughout the factory, is greatly simplified if there is a 
systematic storage of work in process. This result cannot 
be secured by planning on paper alone, no matter how com- 
pletely and extensively this planning is done. The work 
itself should be distributed in such a definite and orderly 
manner (and in a shop swept clean of everything not used in 
the business) that the condition of the flow can be vizualized 
by looking at the work — without reference to paper rec- 
ords. This brings us to a matter which deserves special 
consideration. 

Planning with the Material Itself 

In order to treat this matter thoroughly, it is necessary 
to trace the steps that must be taken to reach a position 



INSPECTION'S RELATION TO PLANNING IOI 

where planning with the material in process is possible. 
Planning, in the broadest sense in which the term is used, 
has developed certain mechanisms in addition to its first 
work of preplanning the routing of work. Thus it must be 
considered as inclusive of the preparing of schedules of 
quantities of work to be produced at given times ; and of the 
dispatching of work at rates in conformity with these sched- 
ules. To this will now be added the planning of space 
assignments for work in process. 

Only the high-spots can be touched upon, with reference 
to the details involved in such planning, but that is really 
all that is necessary, because the other details will readily 
suggest themselves when the general scheme is applied to 
a concrete case. It should be kept in mind concurrently 
that the inspection department can be made the principal 
instrument, and a mpst economical one, in giving life to the 
planning department's work, when the time comes to trans- 
late plans into action. 

Master Planning 

Let us assume now that an article has been designed and 
is ready for manufacture, and that the planning force is called 
upon to preplan for producing and bringing to assembly 
given quantities of parts which meet certain stated standards 
of quality, and for assembling these parts into the complete 
articles. It is assumed at the outset that the management, 
in conference with the principal department heads, has 
developed and approved a general plan for carrying out the 
project; also that this plan has been drawn up by the plan- 
ning department in the form of a master control sheet or sheets 
for the guidance of all concerned. Among the data shown 
thereon would be a list of the things to be done (i.e., the 
whole project is analyzed into its parts), the department or 
individual responsible for carrying out each part of the 



102 THE CONTROL OF QUALITY 

work, and the time when each part of the work should be 
started and completed in order to secure co-ordination of all 
the parts. 

As the drafting-room takes up the making of working 
drawings and special tool designs, the planning department 
in co-operation with the drafting-room should make up a 
complete list of parts and subassemblies, together with the 
tentative outlines of bills of material, which last may later 
be entered on the appropriate plans. The first draft of 
material requirements is then taken off for the guidance of 
the purchasing department and the storeskeeper, so that 
they may make their preliminary arrangements. 

The Operation Mark or Symbol 

With a complete list of component parts and subassem- 
blies in hand, it now devolves upon the planning department 
to devise and apply a set of symbols, as some such device is 
a sine qua non to an orderly and systematic control of the 
flow of work. If the factory does not have a satisfactory 
symbol system already it is suggested that a combination of 
figures and letters may be used to advantage. 

In building up such a scheme of symbolization it is im- 
portant to distinguish between the symbol for a particular 
manufacturing operation, and the number which indicates 
the order or sequence in which the operation is to be per- 
formed. Such an operation may be defined as meaning any 
one application of a mechanical or other process in the 
course of making some one part. Drilling is a mechanical 
process. Drilling a hole for the hinge-pin in the shackle 
of a given model of a lock is an operation. In this case 
the mechanical equipment for the operation would be a 
light drill press, drills, a drill jig, and a limit plug gage. 

The first layout for processing the job of making this lock 
shackle might list the drilling of the hole as the fourth opera- 



INSPECTION'S RELATION TO PLANNING 103 

tion to be performed on the pieces. Later on, the order of 
processing might be changed to permit of improvement, or 
for some other equally good reason. A way might be found 
to eliminate some of the earlier operations, or additional 
operations might have to be inserted, so that the operation 
of drilling the hole might become perhaps the third, perhaps 
the tenth in order of sequence. Now it is of considerable 
value to have some one permanent mark or symbol for des- 
ignating the operation of drilling this hole, if for no other 
reason than cost-keeping. In shops where the attempt is 
made to make one symbol do for indicating both the opera- 
tion and its sequence, the cost of operation No. 11 03 may 
cover drilling this month and grinding next month. Con- 
sider the effect on the tool storage and supply system alone, 
as well as on all quantity and quality records. 

Operation Mark to Remain Unchanged 

It is to be understood then, that the operation mark 
is assigned once and for all to a given operation, and never 
changed. If the operation is abandoned, so is the operation 
mark. If there are twenty operations in making a part 
and it is found necessary to provide another operation, the 
new one is marked as the twenty-first, without reference to 
the place where it is inserted in the list of operations. This 
mark is then used in correspondence, on plans, in marking 
tools, tool storage bins, and so on, wherever and whenever it 
is necessary to refer to the operation or anything connected 
with it. As stated before, no attempt is made to make this 
symbol designate the sequence of the operation's application. 
The matter of sequence is covered, when necessary, by a 
separate number entirely divorced from the operation mark ; 
but the sequence number as such is not required to anything 
like the extent that the mark is. When the operations are 
listed, a separate column should be provided for entering 



104 THE CONTROL OF QUALITY 

the sequence number for each operation; and a corrected 
list should be furnished for the guidance of the shop when 
changes are made in the order of performance of operations. 
If route tags are used with each lot of parts, the sequence is 
indicated by the order in which the operation marks are 
listed, or the sequence numbers may be printed opposite the 
corresponding marks. (See Figure 19, page 108.) 

This scheme for symbolizing applies to the factory prod- 
uct, its component parts, the operations used in manufac- 
turing them, and the equipment strictly related to such 
operations. It does not apply to the symbol system used 
for designating parts of the factory itself, or the machine tool 
equipment, which should be provided for separately. If 
you have a system in use which is giving reasonable satisfac- 
tion, by all means use it in the shops as well as in the office, 
the important point being that something of the sort is 
necessary to bring order out of chaos and to permit a sys- 
tematic and orderly arrangement of work in process. 

The Operation Data Sheet 

The next step in planning involves the assembling of all 
the information the shops should have relative to the proc- 
essing that is to be followed in manufacturing the parts and 
putting them together. It is suggested that an operation 
study sheet of standardized form (see Figure 17) be used in 
developing and recording the process information for each 
part, and that from this there be compiled an operation data 
sheet (Figure 18) for shop use. 

It is believed that the preceding discussion, relative to 
the distinction between the sequence of an operation and its 
distinctive mark or symbol, will make clear the data to be 
entered on this sheet. All the machine tool equipment 
will be labeled or otherwise suitably numbered and marked 
for inventory purposes at any rate, and these individual 



INSPECTION'S RELATION TO PLANNING 



105 



P> 



g 



a. 
E 
o 
U 

tn 

6 

u 

< 






o 
+j 

C 

S 



IU 
LU 

X 

to 

> 

Q 

D 
h 

Z 

o 

< 
a. 
uj 
d 
O 



CQ 



u 1- 



O 






io6 



THE CONTROL OF QUALITY 



-t- 




llH 




Pij 




<N 




C3 






h 


H 


- 


£ 





a 


PQ 


£ 







w" 


- 


^ 


n 


< 


U 


A 



H 
W 
W 
X 
en 

< 
H 
:< 

Q 

Z 
O 

H 
< 

w 

Ph 

o 



p 

M <N 



Pi ~ " « 

Z fa 



Q 



28g| 



w 

Q 






o o o o O ~ M 



rt- Tt- Tt- ^r tj-. 



W <N <N „ 



4j- "*■ 4i- 4-^ 4 



■*■*■<*•► 



pioipipipipipipipipipipipipipi 






H M H\D M 



h^-n. 



■£> =5 



e 

.3 ."y o 



* T3 



0) 3 0) 

be tj — 
rt .2 



U 



ir m o 
a a! ■ 



3 C 0) 
•y "3 bJO 



<U(i.^hOfcUUHO<fcD-0 



12 °-n 

en •- T3 



33 O 



9! o 



INSPECTION'S RELATION TO PLANNING 



107 



h-t 












hH 










(-H 






- 






1— 1 


























c 






be 
a 






*j 




JV 










CU 
























CU 




> 










> 












rs 






r3 
































§ 






S 








u 










»- 
























>- M2 




<u 










<u 
























CU 5 




J4 










.* 












x ■ 






X 






^ ^ 


















CU 










-n 






si 






!ri ^ 




<u 










PQ 


S 










^ cd 

■HlN ^ 
















CM 










cm 












<o 






CO 






<N 




=*= 










TVs 












=*= 






=#= 






=*= 








































;§ 


m 




CO 


co 


CO 


-i- 






-t- 


■* 


-1- 


t^ t^- 


t^ 


1^ 


00 °° 


X) 


X 


vO ^O 


^0^ 




































CN 0) 


M 1 


4t- 




4t- 


-+ 


•+ 


4j- 






■* 


4 


-t- 


4f -*■ 


-+ 


-f 


4t-/J 


-i- 


■* 


4h "*■ 


4^ 


flH 




IH 


£ 


ta 






IH 


fclH 


£ 


fclH 


£ 


fchh? 


Uh 




bbbb 






bbbhhhbbbbUHbbbb 


tf 




Cci Pi C* ffJ 






piOiOi0iPi0<(^Pi<^<^OiQif^P^Pi; 


M 




CM 


N 


CM 


M 






cm 


M 


CM 


CM 0) 


CM 


CM 


0) 0) 


M 


CM 


<N CM 


O CM 


CO 




CO 


rO 


CO 


co 






CO 


to 


CO 


CO CO 


CO 


co 


CO CO 


CO 


CO 


CO CO 


CO co 


" 




- 


O 




» 






" 


O 
1C 






O 






O 




M O 


- 










































































~2 




.s 


Si 










3 


J3 




















c 

cci 




°n 












'C 






















-C 




a 


'■£. 










a 


is 




















en 


CU 


en 












X. 


























D - — ' 






CO 




0) 








CO 




CU 


CO 




aj 


CO 




0) CO 


-2 


3 3 


'O 


U 


Id 


to 


'— 
3 


_oj 





Si 

U 


Ih 
0) 


CO 

1) 


3 OJ 





to 
1) 


3. « 

3 a; 


1) 


-co 


3 <u 


"3. m 

E be 


.s's 


1C 


S 


3 


be 


X 


*0 


10 


S 


3 


tut) 
ctj 


4-» — ^ 

.2-3 


3 




* 


3 


or 


.3 3 


Uh U 






O O fa U 






UOfcUUOfcUUOfcUhO 


S- 










u 






























4-) 













S 1 










E 






E 






O 


S" 


CJ u 













en 










cd 






crj 






CU 


CO 













'57 


"3 

c3 










CU 

be -M 

.s ™ 






-o 






."2 
'55. 4) 


'8 

U2 


c 


-0 
























.3 M 






<D f* 




-Si <u 


c 








<u 


0) 










13 - 












CU "- 

a. w 

CO 


01 


rs > 


CU 








tj 












x 






"o J3 






h> 


'35 O 


u 








'iD 













be 






be 









O 


rt 










C 










3 






3 









— u. 


CU 










u 










— 






— 








u 


r3 be 


u 








~ 


M 










~ u 






r3 u 






.-3 -3 


be 








































2 










*5 












« 






*S 






<5 




CO 










-t- 












t^. 






00 






O 






































01 




M 










CM 












cO 






-t- 






10 














1-1 


















1— 1 











o 



io8 



THE CONTROL OF QUALITY 



machine numbers may be entered on the operation data 
sheet, if additional clearness is required. 

Special tests should be entered as separate operations. 
Inspection points may be mentioned in like manner, or re- 
ferred to by some designating mark, or left out altogether, 
depending on the character and relative complexity of the 
work. Operation data sheets should be made out for each 
subassembly, and for the final assembly, just as in the case 
of each component part. 

A similar sheet showing alternative routings, or sequences 

of operations to be followed 
in case of emergency, may 
be developed for each part ; 
but as these will not be used 
frequently, it is probably 
simpler and better practice 
to show this information 
in chart form. 



Route Tags 

From the operation 
data sheet it is a simple 
matter to work up printed 
route tags, if these are re- 
quired, to go with each lot 
of parts. Under the system 
proposed, no mention of the 
sequence of operations need 
be made, as this will be cov- 
ered by the order in which 
the operations are listed. 
The data taken from the 
operation data sheet for in- 
corporation in the route tag 



Pifces O 8 ° BB1 
Order No. Lot No. 


DATE 


EBP. 
NO. 


OPERATION 


OPER. 
MARK 






Swage Catch Hole 


49 






Shop E-1-1 || out 


In 






' File T Slot Burr Catch Hole 


50 






Shoo B-2 1 out 


in 






R.Pol.SideEnd&CornerPom. 


41 






Cut Down Under Pom. 


85 






Fin.LtSide,Under&Chamfer 


158 






Shop C-7-7 || out 


in 






Corner Slot.Mill 


87 






Corner Slot File 


88 






Shop E-1-1 | out 


in 






Assemble and Fit Catch 


51 






Shop B-2 || out 


in 






Rough Polish Edge Guard 


89 






Rough and Finish Pol. Pom. 


156 






Rough and Finish Pol. Guard 


157 






Pol. for Gage 


61 






Shop B-1-1 1 out 


In 






Edge 


67 






Finish Points 


152 






Shop c-1 II out 


In 






Fit to Gage 


53 






Stamp 


55 






Brown 


56 






Shop C-B || out 


In 






Sand Blast 


58 






Shop E-1 | out 


In 






Wash and Oil Pom. 


69 






Assemble Grip 


60 






Straighten Tang 


68 






Swedge T Slot 


63 






Shop B-3 







Figure 



19. Route Tag — -Remington 
Arms Company 



INSPECTION'S RELATION TO PLANNING 109 

then consists only of the shop symbol or name, and the 
operation mark or symbol. (See Figure 19.) 

The route tag, and in fact all planning work, will be 
simplified if shops are designated by number or letter rather 
than by name. A simple but effective plan is to assign a 
letter to each building; to number the floors, beginning with 
the basement as No. 1 ; and then add a letter to locate the part 
of the floor according to compass direction. 

The Manufacturing Schedule 

In tracing the steps to be taken by the planning depart- 
ment in order to reach a point where planning with material 
is possible, it now becomes necessary to work out the daily 
or weekly production schedule, upon which the design of 
the space assignments for material in process is to be based. 
Suppose the production schedule contemplates an output of 
1,000 complete articles during each working day. This 
means that somewhat more than a thousand of most of the 
component parts must be produced daily, for the reason 
that a few will be spoiled in the assembling department, or 
for some other reason will cease to be available. Then in 
the case of each part, this quantity of 1 ,000+w pieces must be 
increased by the estimated losses at each operation as we 
trace it back through the various steps in its manufacture, 
so that material for perhaps 1,200 pieces of the part in ques- 
tion must be started into production at the first operation 
each day, in order to maintain the schedule with certainty. 

Allowance for Losses in Process 

The losses at each operation which are allowed in pre- 
planning, should be checked in practice by comparison with 
reports supplied to the planning department by the inspec- 
tion department. The importance of making an adequate 
allowance for loss of work in process should be realized and 



110 THE CONTROL OF QUALITY 

it may be noted at this place that the percentage of loss for 
most economical production at each important operation 
may be worked out quantitatively for the planning depart- 
ment by the inspection department as the work proceeds. 
The inspection department, for example, may tighten up or 
loosen up, on such .part of the work as it is in a position to in- 
fluence by its personal judgment (i.e., work that is question- 
ably close to the limits) ; and then report back to the planning 
department the total production and totals of rejected work 
corresponding to the different degrees of inspection applied 
in the tests. It is then up to the planning department to 
compute the corresponding total costs, including losses, and 
set the standard percentage of loss to which the inspection 
department should hold the work in order to recover the 
greatest economy in production. This percentage loss 
may be reduced later when improvements in workman- 
ship and equipment warrant. 

The production schedule just referred to is for a uniform 
flow and therefore should be supplemented by a gradually 
increasing schedule for use in starting into production. A 
similar schedule should be used in tapering off production 
to prepare for changing models. 

Determining Quantities of Work in Flow 

The planner is now in a position to prepare a table show- 
ing the quantities of work to be provided in the banks of 
material at each stage of manufacture in order to insure a 
continuous flow of work. In brief but complete form 
this will include: 

i. The maximum and minimum quantity of raw ma- 
terial to be carried in raw-stock stores for each 
part. 
2. For each operation the minimum quantity of ma- 
terial in process waiting for the next operation. 



INSPECTION'S RELATION TO PLANNING III 

The maximum quantity should be specified, but is 
not of great importance. 
3. The minimum and maximum quantity of finished 
parts to be carried in the finished-parts stores as a 
bank between the producing shops and the assem- 
bling department, including similar data for sub- 
assemblies. 

These assumed quantities will be adjusted later to bring 
them into accord with the conditions as they develop after 
production is under way. 

There is no exact rule that can be followed in fixing 
upon the maximum and minimum quantities of parts to be 
carried in the banks of work in process. Generally speaking, 
it is safe to allow a day for any one piece to pass each opera- 
tion, and therefore it is well to provide for a minimum supply 
of a half-day's work, and a maximum of from one to two 
days' work, depending upon the local conditions. 

The Design of Space Assignments for Planning with Material 
It is now proposed : 

1. That the table of quantities of material required at 

each operation, in order to maintain uninterrupted 
flow, be used as a guide to compute the space re- 
quired to store each maximum quantity. 

2. That layout plans be made for each shop, on which 

a definite space is assigned to each such bank of 
material, in the same way as machines are shown. 

3. That the space so assigned be designated in physical 

form, if the class of work will permit (and it 
usually will), e.g., by boundary lines on the floor. 

4. That each space so assigned have the symbol marked 

thereon, and that the maximum and minimum 
quantities either be shown in figures or at least be 
readily accessible for reference. 



112 THE CONTROL OF QUALITY 

This contemplates, it will be observed, an extension of the 
best factory raw-material storeroom practice to the storage of 
material in process in the shop. This is for the purpose of 
reaping the advantage accruing both to quality and quan- 
tity of output by keeping work in process under positive 
control at all times and places. 

The objection most frequently advanced against such a 
plan is that there is not enough room in the shop. As against 
this view, it is submitted that there is always more room 
when things are systematically arranged. But to carry out 
an orderly arrangement of work, it should be borne in mind 
that it is idle to try to have everything in its proper place, 
unless the proper place in question is clearly indicated. 
This last is no difficult matter. It is a common practice to 
paint aisle lines on the shop floor, and what is proposed is 
merely an extension of this scheme. 

For example, if the shop building is wide there probably 
is a space in the center which is not well lighted. This space 
can be ruled off for the orderly storage of work in process. 
Or the best arrangement may be to utilize spaces between 
machines, or next to columns, or possibly under the windows. 

With the added refinement of having the quantities to 
be carried in these storage spaces either marked near them, 
or otherwise made readily accessible, it is possible to walk 
through the shop and observe the condition of the flow of 
work without the necessity of resorting to paper records to 
discover how things stand. It is exactly comparable, in 
principle, to checking up the stock of a well-arranged store- 
room by a simple visual inspection. For practical purposes, 
it has the great merit of speed. You do not have to wait to 
find out what you need to know. 

This is what is meant by "planning with material" — a 
term here used to distinguish the method from planning on 
paper, which process it extends and supplements. It rep- 



INSPECTION'S RELATION TO PLANNING 113 

resents indeed a culminating point in the system work of 
planning. 

Inspection and Dispatching 

Let us assume now, that we have an orderly condition of 
things in the shop, and that the inspection force is reason- 
ably efficient and on the job. No very great additional 
burden will be placed on the inspectors if they are given the 
added task of the custody of work in process. The inspector 
will see that work is moved to the next bank (or operation 
storage space) as soon as it has been passed by him. Con- 
currently, the inspector will assist in dispatching work in 
accordance with the schedules. 

When the flow gets out of balance at some point it 
devolves upon the inspector to direct the production depart- 
ment's attention to the fact if the foreman is not already 
aware of the situation. If the condition is a serious one, 
and a bad choke-point is resulting therefrom, the produc- 
tion department may resort to overtime work, or prefer- 
ably to the use of an extra shift. There is nearly always 
work for such a balancing shift of all-round, or "handy," 
machine operators to help maintain a uniform flow in a large 
factory. 

Doubtless there are many other methods for controlling 
the flow of work. At one time I visited a factory in which 
the flow was controlled by limiting the daily output of the 
fastest operators, although the superintendent did not so 
designate the process. He stated that on certain operations, 
which were indicated, the workmen were through with their 
day's work when they had completed a fixed number of 
pieces, and that this made it a very simple matter to keep 
the slower operations from being swamped. Surely this 
is a simple and direct method of insuring a balanced con- 
dition of flow, but how about its reaction on the whole 



114 THE CONTROL OF QUALITY 

matter of production? The inspection force was available, 
and could have been utilized, under a properly organized 
plan, to keep the shop in balance as well as in a far more 
orderly and workmanlike condition, without stopping work 
at any process. 



CHAPTER VIII 
CENTRAL INSPECTION 

The Most Advanced Form of Inspection 

The greatest possibilities of controlling the flow of work 
in process, by planning with the material itself, are realized 
when conditions permit that inspection be centralized and 
physically separated from the rest of the shop. Further- 
more, the control of both production and inspection reaches 
its highest development under this system. While central 
inspection is the most highly specialized form of inspection, 
its use need not be so restricted as might appear. For work 
that is done in large volume, central inspection provides by 
far the best means for controlling manufacturing conditions. 
This statement holds good even if the amount of inspection 
to be performed is relatively small, because central inspec- 
tion provides, in addition to the inspection feature, a better 
chance to issue work and record individual production in an 
orderly and accurate way. 

Not Restricted to One Form 

Central inspection may take many forms, and is not re- 
stricted in its application to the business of making small 
interchangeable parts in quantity. The basic principle of 
widest application is that of physically separating inspec- 
tion from production. In the weave shed of a textile plant, 
for example, there would natually be some sort of inspection 
or patrolling supervision of the work on the looms. Central 
inspection would hardly be looked for. Yet the practice of 
removing the goods to a separate inspection room after 
weaving (where they are rerolled, measured, graded accord - 

115 



Il6 THE CONTROL OF QUALITY 

ing to quality, and the defects indicated by some system of 
marking) is nothing if not centralized inspection. (See 
Figure 43.) It will be apparent from the following that the 
principle can be extended to embrace many different sorts of 
work, with all the advantages from the more special use of 
central inspection in strictly interchangeable manufacturing. 
A natural restriction to the application of central inspec- 
tion is encountered when the work is too bulky or too heavy 
to warrant moving except from machine to machine. Never- 
theless, it should be noted that central inspection can be 
used for much larger and heavier work than is ordinarily 
supposed to be the case, provided full use is made of modern 
handling devices. For example, large military rifle stocks, 
which are heavy and bulky in the earlier stages of manu- 
facture, have been handled in shops under central inspec- 
tion, by transporting them in lots of as many as 40. In this 
case, they were carried in a double rack mounted on large 
casters. Other large and heavy parts are often carried on 
lifting truck platforms, designed to carry a definite number. 

Value of Self-Counting Trays 

The use of special carrying trays of the self-counting 
variety should be extended. They are inexpensively made 
of wood, protect the pieces from damage, and save much 
time in counting work. For example, suppose the problem 
is to provide means for handling in quantity a part approxi- 
mating T in shape — a shape which typifies the general form 
of many parts. In the earliest operations of its processing, 
it may be handled in bulk in ordinary metal tote boxes, hold- 
ing, say, 200 pieces. As the processing advances, opera- 
tions are encountered that remove metal down to or near 
the finished surfaces. It is now an economy to keep the 
pieces from injuring each other. Carriers should be made, 
preferably of shellacked wood, of rectangular form to sup- 



CENTRAL INSPECTION 1 17 

port 100 parts, in, say, 10 rows of 10 pieces each, and ar- 
ranged to permit stacking. 

The objection to open bottom containers of this type is 
that oily work drains onto the floor, but most of this trouble 
can be avoided by providing a draining pan under the tray 
of work at the machine. As just stated, tote boxes of this 
character serve a very useful purpose in assuring a finer fin- 
ish by protecting parts from the little scratches, dents, and 
cuts that so detract from quality. Their principal value, 
however, flows from the self-counting feature, which sim- 
plifies the labor of securing an accurate count, and does 
away with arguments as to the number of pieces issued to, 
or received back from the machine operator. Central in- 
spection almost necessitates something of the sort to develop 
its greatest possibilities. 

In this connection attention is invited to Edward H. 
Tingley's article on "Making the Truck an Asset in Man- 
agement," 1 from which the following is quoted (see also 
Figures 20 to 23 inclusive from the same article) : 

Speeding Up the Work of Operators, Inspector, and 
. Storekeeper. The workman expects any system for handling 
material to help him increase his productive capacity as well as 
decrease his effort. The special trucks illustrated have these ad- 
vantages, as they occupy a minimum of floor space and allow the 
work to be brought as close as possible to the machine. The trucks 
are easily moved by one man, and with work stacked on both sides 
they can be turned around to bring the other side to the machine, 
thus eliminating useless walking. The construction of the truck in- 
sures the separation of the pieces and so prevents damage to any 
finished or ground surfaces. It also suggests the idea of order and 
care to the workman, and it gives him the satisfaction of seeing his 
work progress. He unconsciously sets a goal for himself, endeavor- 
ing to complete a row or truck by noon or night. The amount on 
the truck is proportioned to what one man can push around and 
also what will make a good quantity for piecework operations. 



1 Management Engineering, Nov. 1921. 



n8 



THE CONTROL OF QUALITY 




CENTRAL INSPECTION 



119 



The work of the inspector should be as limited as possible, as his 
work is indirect labor, an item of overhead expense. In any well- 
regulated factory the foreman should be fully responsible for the 




Figure 21. A Wood Frame Truck 

This type is used in the armature department for handling the armatures when 

complete. 



quality of work produced, and the inspector should merely check the 
foreman. If the truck, box, or rack in which the material is handled 
will permit of quick and accurate counting by the inspector, easy 
removal and quick replacement after inspection, the time of the 
inspector can be reduced to the minimum. Through the use of 



120 



THE CONTROL OF QUALITY 



trucks such as shown by the illustrations in this article, counting is 
unnecessary, as the inspector knows from the Production Order 
card the total number the truck or box should contain, and only 




Figure 22. An "A" Frame Wood Truck for Connecting Rods 

The rough forging is placed in the truck in the raw-stock room and the finished 
rod is taken off in the finished-stock room. 



has to subtract the missing pieces from this total. This counting 
of .the missing parts can be done at a glance. 

The finished parts stockroom is also benefited in several ways by 
the special trucks, as the counting of material as received is ex- 
pedited and a visual inspection can be made in a short time. If the 



CENTRAL INSPECTION 



121 




122 THE CONTROL OF QUALITY 

material is to be stocked in bins, the truck can be pushed to the loca- 
tion and emptied as desired. Frequently the material is to be used 
in other assembly operations, and if allowed to remain on the truck 
it can be sent at once without further work to the assembly depart- 
ment. In preparing material for group assemblies the special trucks 
can be loaded in the finished parts stockroom with speed and the 
assurance that no damage will result while in transit, and that the 
count is correct as to the number of pieces sent out. 

Operators working on a piecework basis will not try to claim 
pay for the full amount of the order if some parts are missing, as the 
evidence of such missing pieces is open to the time clerk and the 
foreman at a glance. In the matter of placing the responsibility 
for scrap it is very easy for a foreman to check the actual amount of 
material coming into his department in order to be sure that the 
Production Order shows the amount scrapped on previous opera- 
tions. This is a factor frequently overlooked in the design of 
equipment to move material. 

The Two-Bin System Extended 

Consider an application in the shop of what Dr. Fred- 
erick W. Taylor, I believe, called the "two-bin" system. 
Its application in modern storehouses is generally known. 
For each article stored and issued with any frequency, two 
storage spaces are provided instead of one, as usual under 
the older system. Or perhaps it would be more accurate to 
say that the storage bin or other space is divided into two 
parts, A and B. Issues of stock are made from A until it 
is empty. Meanwhile new stock is accumulated in B, as 
it is received in the storehouse. As soon as A is empty 
the storekeeper begins to issue from B, and to accumulate 
new stock in A, and so on, alternating the issuing bin, 
which is indicated by a tag or movable indicator. In 
this way no old stock is permitted to lie in the bottom of 
the bin, as is almost certain to be the case when new stock 
is piled in on top of old stock in the single-bin system of 
storehousing. 



CENTRAL INSPECTION 1 23 

Systematic Layout for Material in Process 

A continuous flow of work through the shop indicates the 
desirability, and perhaps the necessity, of laying out the 
storage spaces, for banks of material in process, on the two- 
bin system. For example, with banks carrying a day's 
supply the two-bin scheme can be worked by issuing from 
one end of the pile today, from the other end tomorrow, and 
so on, alternating each day or each shift if the flow is rapid. 
Under a system of central inspection the storage spaces for 
material should be systematically arranged with this object 
in view. Needless to say, control of the flow is much sim- 
plified under such an application of central inspection. 

As a preliminary step to taking up the arrangement of 
the shop under central inspection, attention is invited to the 
following diagram (Figure 24), which indicates the theo- 
retical line of flow of work : 

First Operation Second Operation 



Sx > P, 



> Ii 



P., 



->etc. 



Figure 24 



S represents the stores of raw material for the part in 
question, which is daily or hourly issued to replenish the 
material waiting for the first manufacturing operation at 
the process storage point Si — preferably arranged in two 
parts, or piles of work, on the two-bin system, and in self- 
counting tote boxes. From Si the work is issued as needed, 
one box at a time, to the operator at the production point, 
Pi. The production point in question may be one machine 
or a group of machines, under one or several operators, or 
it may be a bench job or some special test. After the oper- 
ator at Pi finishes the box of work, it is removed to the in- 
spection point I h where it may be inspected in whole or in 
part (in whole only if 100 per cent inspection is required) or 
perhaps merely counted by the inspector. After the inspec- 



124 THE CONTROL OF QUALITY 

tion, the tray of work is moved to 5 2 , the storage point for 
work waiting for the time being for the next manufacturing 
operation. When certain parts are rejected and a "broken" 
box results, the box should be filled up from the next box of 
parts or from a small stock kept for that purpose in the in- 
spection room, so that only full boxes are issued from £2 
to P 2 , and so on. 

Layout of Central Inspection Crib 

In centralizing the inspection into a central inspection 
system, we bring together in a central place and in accord- 
ance with some convenient arrangement all of the storage 
points (or banks of material in flow) and the inspection 
points, leaving in the shop proper nothing but the produc- 
tion points, together with such work as is actually being put 
through the machines at the production points in question. 
This means, when the system is carried to the limit, that 
after working hours all work in flow will be in the central 
inspection spaces, and therefore there will be no work at 
the machines, which condition insures a complete count 
of each day's work and tends to prevent trouble of various 
kinds, including the temptation to steal parts. 

In concentrating the storage and inspection points at 
some central place or places in the shop, the greatest econ- 
omy will be secured by a shop arrangement that reduces the 

distances between any two 
consecutive points in the line 
of flow, Si, P h I s , S 2 , P2, I2, 
S s , P s , 1 3 , etc., as much as 
possible. For example, a 
good arrangement would be 
that shown in Figure 25. 

The dotted line indicates 
the separation between the 



p, 


P 3 


3) 


I: 


I a 


I.Setc. 

[ 


Si 


s» 


4 


S10 


S u 


s 12 j 


I 10 


In 


lietc. 


P» 


Pa 


Pin) 




Figure 


25 



CENTRAL INSPECTION 



125 



shop proper, with its production points P u P 2 , etc., and the 
central inspection space or crib containing the correspond- 
ing storage points and inspection points. 

As a matter of fact, the diagrammatic arrangement just 
shown gives an erroneous conception of the quantitative 
space assignment required, because / and 5 ordinarily re- 
quire much less space than P. Frequently / will represent 
only a counting of the work, without inspection. It is in- 
teresting to note, however, that a uniform distribution of 
work in flow (especially when standard sized tote boxes are 
stacked in piles) carries with it the condition that the spaces 
provided for all storage points be the same in size. The 
same thing can be expressed in much shorter form by say- 
ing that Si = S 2 = S 3 , etc., which, incidentally, is a nice ex- 
ample of the saving in time from the use of symbols. 

It is very likely, therefore, that the following diagram 
(Figure 26) more accurately shows the relative size of the 
space assignments for such an arrangement: 

Pi P 2 P, etc. 



I, 

S, 






u 



s 3 s ia 



P12 etc. 



Figure 26 



Construction of Central Inspection Cribs 

It does not follow, by any means, that the collection of 
the points 5 and / in a central inspection space requires 
that this space be separated from the rest of the shop by 
partitions. That is a question which must be settled by the 
class of work involved and by the conditions attending its 



126 



THE CONTROL OF QUALITY 




Figure 27. Transporting Rack for Rifles — Remington Armory, Bridgeport 

Note especially the construction of the type inspection crib in the background. 



CENTRAL INSPECTION 



127 



manufacture. In many instances it is only essential that 
the central inspection space be indicated by lines painted on 
the floor, or by some other means of showing the physical 
separation of the principal functions that has been made. 
A light railing may suffice. 

When the use of a partition is indicated by the local con- 
ditions, one of the best plans is to erect a light framework, 
supporting woven wire to a height of 6 or 8 feet. Chicken 



Braces- 



Support 
2'k 4" - 



Closed in by sheets of 
fiber board where 
female inspector are 
employed. 



-Woven wire, inside of supports 



Gage & inspection 
instruction cards, 
sample parts, etc. 




s-» 



Aisle- 



Figure 28. Type Section of Central Inspection Crib 



wire will do. (See Figure 28 showing a type section of a 
central inspection crib.) 

The woven wire is preferably put up inside the line of 
supports. This arrangement avoids lost space and objec- 
tionable holes behind the inspection benches on the one 
side of the central inspection crib, and permits more or- 
derly storage of work in process banks on the other side of 
the crib. 

When partitions are used, it becomes necessary, of 
course, to provide openings through which work may be 
passed. If the work is bulky and each storage unit of parts 



128 



THE CONTROL OF QUALITY 



is carried on wheels, for example, the opening should ex- 
tend upward from the floor to a height just sufficient to per- 
mit the comfortable entrance of the carrying device. Smaller 
parts, that are handled in tote boxes or trays, usually require 
only a passing window with a shelf. These windows should 
be spaced close enough together to avoid too long distances 
from machines to windows. At the same time they should 
be spaced far enough apart to avoid interference with the 
inspection benches. It is not good practice in this case, nor 
is it ordinarily necessary, to have the machine operator de- 
liver his work directly to the inspector who is to inspect and 
count it. There is far less chance of connivance between 
inspector and workman, together with less interference with 
the actual work of inspecting and counting, if the work is 
issued and received by the working foreman in the inspec- 
tion crib, or perhaps by an assistant. Women inspectors, 
for example, may be employed on quite heavy work if they 
are relieved from having to lift tote boxes full of parts. 
When the flow is rapid, a worker of the common labor class 
will be fully employed in moving tote boxes to and from the 
issuing windows and the storage points. 

Referring again to the typical diagram, the introduction 
of partitions with passing windows, or doors, brings about 
the arrangement shown in Figure 29. 

P^ /P P\ ^PP-^etc. 



V>etc. 




P P P pp-»etc. 

Figure 29. Floor Plan of Central Inspection Crib 



CENTRAL INSPECTION 



129 



An Adaptation to Rough Work 

It is now proposed to show the application of central 
inspection in two cases, illustrating the extreme conditions 
that are likely to be encountered. The first example is that 
of a shop making a relatively small but bulky article, such 
as heavy canvas bags. The processing involves cutting the 
canvas and folding once, sewing the side seams, binding over 




Elevators, 
Stairway, 
Washrooms , 
etc. 



Figure 30. Floor Plan of Canvas Shop 



and sewing the top seam, inserting a row of brass grommets 
above the latter, and finally passing a gathering cord through 
the grommets and attaching a fastening device to the. cord. 
The work is counted automatically by the issue of lots of 
100 pieces (on lifting platforms) from a central inspection 
space. Inspection, however, is by sampling at the machines, 
except after completion of the bags, at which stage there is 
a 100 per cent final inspection. In this instance it is less 
expensive to allow an occasional bad piece of work to slip 
through than to provide a closer inspection. 



130 THE CONTROL OF QUALITY 

Each shop was located in a room approximately ioo feet 
square, with machines, work benches, and work in process 
scattered throughout, but arranged in a general way in the 
order of operation sequence. The rearrangement is indi- 
cated in Figure 30. 

One end of the shop was darkened by elevators, stair- 
ways, washrooms, and similar enclosures — a condition fixed 
by the building. The dark space in the middle of the shop 
(indicated by IS) was cleared of machines, which were 
moved out to the light (P, P, P). The center aisle lines 
were closed, and the new aisle lines painted on the floor as 
indicated by the dotted lines. The new aisles were kept 
clear at all times. At each machine, two spaces (or platforms 
for lifting trucks) were located to provide one place for the 
lot of pieces ready for the machine and another place for 
work just passed through the machine. 

The Resulting House Cleaning 

The central inspection space IS was not enclosed, but 
its boundaries were clearly indicated by the arrangement of 
benches and of work in the storage banks. As a part of the 
process of rearranging this shop, the foreman was instructed 
to clean house, and in doing so to be guided by the rule that 
everything not needed and used in the work must be dis- 
carded. After he was through, a wagon-load of junk was 
removed, in the form of unnecessary shop furniture, old 
signs, ancient records, and what-not, extending even to 
bench drawers that served no useful purpose. The subse- 
quent application of a coat of white paint, and the introduc- 
tion of the more orderly and systematic control of work in 
flow, created an obviously different working atmosphere. 
Incidentally the scrap value of the stuff removed paid for 
the direct cost of the clean-up. 

This simple case has been cited for the reason that it is 



CENTRAL INSPECTION 131 

typical of a large class of work (often relatively rough work) , 
to which the general principles and methods of central in- 
spection can be applied with advantage. 

An Adaptation to Close Work in Metal 

Let us now proceed a very long way up the scale of appli- 
cation of central inspection, until we reach the other limit. 
In this case central inspection is to be applied to a shop mak- 
ing in quantity, high-grade steel parts of relatively small 
size — the machining is intricate, the limits are very close, 
the parts are strictly interchangeable, limit gages are in use, 
and the finish must be excellent. In short, the work is diffi- 
cult, comparatively costly, and the standard of quality is 
almost high enough to approximate to that required for the 
very tools used in making the parts. Evidently, there will 
be need for close inspection after all important operations, 
sampling for practically all operations, and 100 per cent 
inspection of all finished parts. Since such work is ordina- 
rily found in large factories, we may assume as well that the 
shop in question is only one of several such shops and that 
it handles the machining of but one of the parts — or at most 
only a few of them — that are to become components of a 
complex mechanism. 

In a case of this kind, central inspection is a machine 
with a vitally important service to perform. Like any fine 
machine it should be designed with the greatest attention 
to details. It may have to be intricate, yet the design 
should follow the simplest and most economical line for 
accomplishing the desired result. Such an adaptation of 
central inspection is the most highly specialized form of 
inspection, and as such is the ideal instrument both for use 
in controlling quality and for insuring a uniform flow of 
work. 

The usual type of factory floor for such work is from 60 



132 



THE CONTROL OF QUALITY 



to 80 feet wide (a greater width interferes with lighting) ; 
some 250 feet or more long; and built with sides con- 
structed of steel and glass sash extending from the ceiling to 
within about 3 feet of the floor. While the glass siding is 
sometimes carried down to the floor, such construction is not 
desirable for work of this kind, as the light shining up from 
below the machines is trying on the eyes and therefore of 
deleterious effect on the work. There will be no really dark 
spaces in the shop, but the light may not be so good at the 
exit and entrance, nor at one of the corners at each end of 



60 



16 bays 



-200 + 



a a a a 

a a 

□ a □ b 



Figure 31. Typical Modern Shop Floor Plan 

the shop, if enclosed fire towers are built in at these points. 
The state laws require that clear passageways be preserved 
from end to end of the shop, for use in case of fire or panic. 
A frequent arrangement of a typical shop floor of this sort, 
as shown in Figure 31, provides for clear aisles at a, a, a, a, 
between the rows of columns. 

Aisle Arrangement 

The aisles bb, connecting shop to shop may be found at 
the middle or end of the room, and since they are used for 
intershop traffic, must always be kept open. 

Whether there are columns or not, it is usual to provide 
for a central aisle, which is kept clear at all times (at least in 
theory). Concurrently, it is necessary to have other aisles 



CENTRAL INSPECTION 133 

paralleling the main aisles, but out among the machines, to 
permit of the passage of men and material to the machines. 
These aisles are not so well defined, unless the machine ar- 
rangement is a simple and orderly one. It should be noted, 
however, that the aisles in question usually can be regulated 
into clear and fairly well-defined passageways, thus per- 
mitting the use of the former middle aisle for central inspec- 
tion. In many cases, especially when combined with central 
storage of work in process, this arrangement will result in 



b 


/a 












c 


a< 1 

\ U- 












1 

J 


\ B 








U 


U 


D 


d 















Figure 32. Modern Shop Floor Arranged for Central Inspection 

an actual economy of floor space, due chiefly to more effi- 
cient use of the space otherwise taken up by work in process. 
There is developed in this way the arrangement shown in 
Figure 32. 

The necessities of transportation and emergency exit are 
met, under these circumstances, in two ways : 

1. At least one fairly well-defined passageway is pro- 
vided among the machines at each side of the shop, along the 
lines abc and ade. There must be a passageway among the 
machines; and since the machines are in fixed locations, the 
principal cause of blocked passageways is eliminated when 
the material at each machine is limited to one standard- 
size lot of parts. 



134 THE CONTROL OF QUALITY 

2. These aisles are supplemented by providing double- 
swing doors (if any are required) at the ends (AB and CD) 
of the enclosed inspection space ABCD. The inspection 
benches and material in process along the sides A C and BD 
decrease the effective width of the former central aisle, but 
not so much as to eliminate the passageway. The side 
aisles are therefore supplemented by a more restricted cen- 
ter aisle, and, all in all, ample gangway is secured. 

There are many other arrangements, of course, in which 
a shop can be laid out to provide for central inspection, but 
the scheme just outlined, while of admitted uniqueness, has 
much to commend it in many cases. It provides a central 
place from which to distribute work, economizes the floor 
space of the whole shop, and can be used in adapting central 
inspection to many shops not originally arranged for this 
system of control. Any such location of inspection cribs 
carries with it a positive requirement for artificial lighting of 
the inspection benches, but this is not a serious objection 
because the more uniform light of good artificial illumination 
has much to commend it for inspection purposes. 

Advantages of Several Centralized Inspection Spaces 

Whether this or some other plan is adopted for the loca- 
tion of the central inspection cribs, it is well to observe that 
central inspection does not imply one inspection room only, 
nor even one room only in each shop. On the contrary, the 
more efficient arrangement in a large shop is to place the 
cribs at the locations where they give the maximum of serv- 
ice with the least interference to traffic. The governing 
conditions should be that each inspection crib be centrally 
placed with reference to the machines it is to serve, and that 
it be large enough to store its proper quota of work in 
process. 

The least interference with traffic is secured when the 



CENTRAL INSPECTION 



135 



crib is parallel to and near the normal line of flow of work. 
It will be found that there is much lost space in the ordinary 
shop arrangement which can be made available if the shop 
layout is carefully planned with reference to the space 
occupied by work in process as well as that taken up by 
machinery. Thus, if there is insufficient room for all of the 
inspection work in the shop itself, the next logical place to 
utilize is some space on the side of the passage from shop to 
shop. It is quite usual to find unused space going to waste 
in these locations. In such case it is clear that this space 
should be utilized for the inspection work that can best be 
spared from the neighborhood of the machines, i.e., the final 
inspection of finished parts, and the salvage or reinspection 
of rejected work. 

Standard Arrangement Desirable 

Reference already has been made to the fact that each 
inspection crib should be designed with great care as to the 
details, but, naturally, each crib should be laid out in ac- 



























w 




w 


< — I 




F 




1 
















□ 

1 


□ 


□ 




□ 


□ □ 


□ 




□ 


□ 


□ 

< 



— S,-> 

—1 r~ 

a 1 b 



~w 



Figure 33. Type Floor Plan of Central Inspection Crib 



cordance with a general unified plan for all of them. To 
illustrate, the outline shown in Figure 33 may be assumed 
to be that of a central inspection crib which is typical for a 
given factory. 

The size of the crib will be determined in a general way 



136 THE CONTROL OF QUALITY 

by the amount of space required for storage of work in proc- 
ess, for the reason that if this space is provided on one side 
of the crib there is pretty sure to be room enough for the 
inspection benches on the other side. The passing windows 
w, w, — will be placed at fairly uniform intervals, but this 
should not be a fixed rule, as the most convenient locations, 
with reference to the number of machines to be served, 
should be selected. 

As the normal work bench with wooden top, back rail, 
foot rail, and metal frame support is satisfactory for the pur- 
pose, a number of them should be placed at i, i— and shop 
stools provided. Reasonable bodily comfort is a great 
relief to the confining tedium of bench inspection. Bench 
drawers are not desirable in most instances. If it is neces- 
sary to provide against the chance of gages being tampered 
with outside of working hours, a cupboard, with a lock, may 
be provided. 

On the side of the crib opposite the inspection benches, 
the space should be marked off for storage of work in flow. 
If the two-bin principle is followed, each unit storage space 
should have two sections, as S x (a) and (b). There is, of 
course, a natural limit in the height to which any kind of tote 
box can be piled with safety and this fact should be con- 
sidered in laying out the storage point. Furthermore, the 
height that corresponds with the number of boxes of work 
required in each bank to maintain the flow should be in- 
dicated on the side of the crib. With these refinements in 
use, each storage point will be shown by a card or other 
mark on the side of the crib, as shown in Figure 34. 

A pointer may be used to indicate the issuing pile, but is 
not necessary if the issuing and receiving sections are re- 
versed automatically at given times. 

The inspection benches should be marked off, or the 
inspection points indicated by labels showing the operation 



CENTRAL INSPECTION 



137 



symbols on the side of the crib above the benches. It may 
be found very useful to supply a gage instruction card, 
telling in detail how the gages are to be applied, and setting 
forth the special points to be looked after. It is often de- 
sirable to furnish sample parts, which should be tied to the 
side of the crib over the bench, to prevent their becoming 
mixed with the regular work. (See Figure 12, page 71.) 

Assuming a di- 
rection of flow 
from left to right 
in Figure 33, the 
inspection points 
will be arranged in 
this order, a sepa- 
rate bench being 
provided at F for 
the use of the 
crib boss or work- 
ing foreman of 
the crib. Among 
other purposes, 
this bench will 

Serve as an issuing FigUre 34 p .\ y P e Arrangement of Material Storage 
& Point in Central Inspection Crib 

point for working 

gages, which is an essential feature of quality control, as 

will be noted later under the subject of gage-checking. 




Summary of Advantages 

The advantages of providing, within the producing shop, 
a central inspection crib combined with a storehouse for 
parts in process, may be summarized as follows: 

1. The work can be stored in self -counting trays. A 
workman will come to the issuing window and obtain a box 
of parts, which he will machine and return. The inspector 



138 THE CONTROL OF QUALITY 

will find that some are good and some bad, and the work- 
man will be credited accordingly. He will be paid for what 
he does — and for no more nor less. This will insure, among 
other things, the collection of accurate data as to what is 
going on in the way of production and will tend to do away 
with losses from stolen, destroyed, or lost parts. 

2. There will be nothing at the machines outside of 
working hours, and nothing at each machine but a box of 
parts at any time during working hours — result, a clean 
shop, and a clear one. 

3. The systematic arrangement of all parts in flow makes 
it possible to check up the flow by quickly visualizing its 
condition, i.e., it is possible to plan with the material itself 
rather than with figures alone. A walk through the crib 
tells the story. 

4. The control of quality is more certain, as the work of 
the inspectors can be supervised to greater advantage and 
the custody of work in process is well centralized. The in- 
formation necessary for inspection can be so arranged in 
useful form by providing each inspection point with stand- 
ard samples, gaging lists giving the symbol of the gage to 
be applied and the percentage of inspection, gage instruc- 
tions, etc. All gages can be issued and controlled from this 
point. 

5. The routing and flow of work is under sure control. 



CHAPTER IX 

THE ORGANIZATION OF THE INSPECTION 
DEPARTMENT 

Designing the Instrument for Controlling Quality 

Before plunging into the particulars of a subject like 
"organization," a term which is often confused with the re- 
lated terms "administration" and "management," it would 
seem to be worth while to make sure at the outset of what 
we mean by "organization." In order to separate out the 
idea, let us first think of the inspection department as a 
machine or an instrument for use in the control of quality, 
together with certain secondary duties to be combined 
therewith as a matter of economy. The organization of the 
inspection department may be considered as comparable to 
the design of the machine, and the administration or man- 
agement of the inspection department as comparable to the 
operation of the machine thus designed. In accordance 
with the foregoing analysis, questions affecting the manage- 
ment of the inspection department will be discussed in the 
succeeding chapter. 

The Development of Organization 

The process by which organization develops may be 
analyzed into three steps: 

i. There is a union or grouping of individuals for a com- 
mon purpose. From this fact, arises a necessity for organ- 
izing. 

2. The work necessary to accomplish the purpose is 
divided and distributed so that each group of individuals 
performs the work allotted to it with undivided authority 

139 



140 THE CONTROL OF QUALITY 

and individual responsibility. This division of duties tends 
to become more complex as the number of persons involved 
increases or as the scope of the work broadens. 

3. The interdependence resulting from the preceding 
steps demands a co-ordinating of the work of the separate 
parts or groups, in order to secure co-operative action, and 
thus to weld all groups into one coherent whole so that all 
work harmoniously toward the common objective. 

Organization begins with the first of these stages, it is 
developed by the second, and is completed and perfected 
by the last. The higher the type of organization, the more 
intricate is the distribution and division of labor; and this 
fact, in turn, calls for better co-ordination, together with 
closer and stronger co-operation. 

In the light of these general observations we may pro- 
ceed to design an organization for the inspection department. 
As we are designing with men as our material the design 
must conform to the capabilities of the men that are avail- 
able; furthermore it must be suited to the conditions im- 
posed by the character of the work to be performed. The 
discussion that follows applies, as will be noted, to the or- 
ganization of an inspection department for a large factory 
doing high-grade interchangeable manufacturing, but the 
same principles apply in simpler cases, and the organization 
may be readily and suitably simplified for such situations. 

The Chief Inspector 

It is almost begging the question to say that if the right 
man is at the head of the inspection department, there need 
be no worries about the organization and management of 
that department. But what type of man is called for? The 
position is one of trust, hence character is an indispensable. 
Good judgment is requisite, not only the judgment that 
flows from "mechanical sense" and skilled ability as an 



ORGANIZATION OF INSPECTION DEPARTMENT 141 

engineer, but also plain "horse sense." In addition the 
man must be an executive of no mean ability. 

Many persons have been so accustomed to regarding in- 
spection as one of the secondary features of manufacturing, 
that they fail to realize what complex and extensive organi- 
zations have been evolved for the inspection departments of 
large factories. It is by no means an uncommon thing 
nowadays to find an inspector for every 10 to 20 workmen, 
and the proportion may be much higher. In the Wahl 
Company of Chicago, which manufactures, among other 
things, the ubiquitous Eversharp pencil, the proportion of 
inspectors is 1 to 8.6 workers. 1 In the S. K. F. Ball Bearing 
Company's plant at Hartford, where every operation is 100 
per cent inspection, 27 per cent of all the productive workers 
are employed in the inspection department. 2 Under diffi- 
cult war conditions, the inspection department of one of the 
munition plants reached a total figure of 2,200 employees, 
and possibly there were larger inspection forces in other 
plants. 

Even under normal conditions, it will be recognized 
from the above figures, the head of the inspection depart- 
ment has an executive job of no mean size. The duty is 
very greatly enlarged and complicated, moreover, by reason 
of the fact that the inspection department is not concen- 
trated into one definitely bounded shop, like the various 
production departments. On the contrary, its work reaches 
into nearly every part of the factory, and in consequence its 
personnel is widely scattered. The character of the work 
is at least as diversified as the processing, which fact still 
further complicates the problem; for the inspection force 
will have one group of workers in the wood-working depart- 
ment, for example, while a thousand yards away it will have 



1 Furnished through the courtesy of C A. Frary, General Manager. 

- Courtesy of R. F. Runge, General Factory Manager of S. K. F. Industries, Inc. 



142 THE CONTROL OF QUALITY 

another group engaged in the inspection of metal parts made 
to standards of accuracy so precise as often to split thou- 
sandths of an inch. Therefore the chief inspector should be 
generally familiar with all shop processes rather than a 
specialist in a limited number of them. 

Duties of the Inspection Department 

Concurrently with selecting a man to take charge of the 
inspection department, there arises the problem of outlining 
what this department is to include. Conversely, the amount 
of work that it is expedient to include will determine how 
big a man should be selected to head the work. The two 
things always go together, and the resulting solution is 
usually a compromise. Obviously, the duties of the inspec- 
tion department will often comprise a number of things 
that, speaking strictly, are not inspection, but they will all 
be related to inspection, and it will be economical and wise 
to include them with inspection, in order to secure a more 
complete control of quality. 

In the first place, there will be the separate inspection 
forces for each main group of the factory's work, as in the 
case of an automobile factory making both trucks and pas- 
senger cars. Each of these main groups will be subdivided 
into an inspection force for each shop, or smaller factory 
unit, including the assembling shops. 

Work Related to Process Inspection 

In addition to this inherent duty, we may list the follow- 
ing: 

i. Raw material inspection, including the necessary 
laboratories, chemical and physical. 

2. Heat treatment inspection, including the metal- 
lurgical and metallographic laboratories. 



ORGANIZATION OF INSPECTION DEPARTMENT 143 

3. Tool inspection, especially if the factory maintains a 

tool-making shop. 

4. Gage-checking and the verification of measuring 

standards, all in close co-operation with the 
chief engineer. 

5. General supervision of the assembling department, 

in some instances, where inspection in this depart- 
ment is of unusual value in guiding the work of the 
parts-making shops. 

6. General supervision of the factory salvage depart- 

ment, when it is specially desirable to safeguard 
production from the return of defective work into 
flow. 

The inspection of machine tools and similar factory 
equipment, as well as of the buildings and their appurte- 
nances, has not been included as a possible assignment of the 
inspection department, for the evident reason that the in- 
spection and maintenance of all these constitute the prin- 
cipal duty of the works engineer. It will be carried out by 
the latter with due regard to the fact that every department 
in the plant will be "on his trail" if he overlooks anything 
that requires attention. 

The general test for deciding whether a particular branch 
of factory endeavor should be included in the inspection de- 
partment is simply this — -"Will the chief inspector handle 
it to the better advantage of the entire plant or not?" The 
answer depends, of course, to a considerable degree upon 
who and what the chief inspector is. 

Undoubtedly the term in widest use to designate the 
head of the inspection department is that of "chief inspec- 
tor." It has grown up in much the same way as the title 
of "chief engineer," and it is possibly just as well to retain 
its use, although there are many organizations in which the 



144 THE CONTROL OF QUALITY 

strict following of the plan used in the general factory organ- 
ization chart would result in the more definite title of "man- 
ager of inspection," or possibly that of "director of inspec- 
tion." The matter of title, however, is of no great moment, 
for the greater one's experience in factory work the less will 
be the emphasis placed upon titles. But there is a matter of 
marked importance which should not be overlooked for an 
instant if the control of quality is to be assured — the chief 
inspector should report directly to the highest executive 
authority in the management, and to him only. 

The Line Organization 

In outlining the organization under the chief inspector's 
jurisdiction, it is believed that the best result will be obtained 
by a combination of line and staff, as in the case of the gen- 
eral organization of the factory itself. The line organization 
will consist of the usual executive heads of the different 
groups of workers, i.e., general foremen-inspectors, foremen- 
inspectors, subforemen or crib-bosses, and so on, making up 
the "chain of command" through whom instructions will 
pass from the chief inspector to the individual inspectors at 
the bench. 

The staff of the chief inspector will consist of a few 
carefully selected specialists who have no executive authority 
over the line executives, other than that which naturally 
belongs to them by reason of the moral effect of their close 
association with the head of the department. 

Arranging the type form of organization in chart form 
results in the arrangement shown in Figure 35. 

It is generally conceded that no executive should have 
more than a limited number of subordinates reporting di- 
rectly to him. This number varies with circumstances, but 
in work of this kind should not exceed ten or twelve at the 
outside, as there is such a volume of small questions requir- 



ORGANIZATION OF INSPECTION DEPARTMENT 



145 










z 





*: 


< 


<_t 





1 










_1 


z 



5 


a 


( > 


< 




111 


LZ 


w 


a. 




i 


z 









a. 

O Q- 


So 




a 






5 

. CO 


tiSs 




(J 


Si£ 




a 


ft* 




n m 




O O- 






oc 
5 






t- 1 a 






■2* 




co 


<* 




a. 












oa 






OC 

r 






H Q- 




c "5 


uiin 




«»: 


#i 





6 
a 


X 


el 


, 


a. 



Co 







CD 


n 


r 
in 




I 






CD 


H 


a 






X 


££ 



t%i 




<■ 


ra-2 


D 


1= Si 










OO 


an 


J 






<- 


n 


V 




T> 


i£-£ 



u 



10 



146 THE CONTROL OF QUALITY 

ing prompt settlement, to say nothing of the demands on 
the chief inspector's time for continuous constructive work. 
Therefore in a concern making several lines of product, 
there should be an inspection superintendent (or a general 
foreman-inspector) in general charge of each group of shops. 
The principal assistant to the chief inspector may very 
well be one of these superintendents. On the chart shown 
(Figure 35) any other departments that may be assigned to 
the care of the chief inspector (such as the laboratories for 
raw material inspection, the gage-checking department, etc.) 
should be added, as separate main divisions, on the line a-b. 
The line c-d of the chart provides for a foreman-inspec- 
tor in charge of each production department, and since in- 
spection is best performed when strictly specialized accord- 
ing to classes or kinds of work, it is suggested that there be 
a separate foreman for each different kind of production 
department in the group, even if this results in considerable 
disparity in the sizes of the forces reporting to the various 
foremen-inspectors. Thus the foreman-inspector of the 
woodworking department in a small-arms factory may have 
several shop floors under his care, while the heat treatment 
department foreman-inspector has only one. In other 
words, the inspection organization should parallel the pro- 
duction organization in this respect, rather than attempt to 
equalize the jobs by combining different small departments 
under one head. 

Special Value of Understudies 

It is specially essential in inspection work that under- 
studies be designated for foremen-inspectors and their more 
important assistants. This arises from the fact that the 
personnel of the inspection department's supervisory force 
must be relied on to a large extent to see that standards of 
quality do not shift; the need is great even when every care 



ORGANIZATION OF INSPECTION DEPARTMENT 147 

has been taken already to fix the working standards as 
definitely as possible. In the work of keeping standards 
from shifting, the inspection foremen accumulate a large 
body of knowledge in the form of small details, which can- 
not be quickly passed on from man to man, but must be 
absorbed from contact with the work. It is therefore very 
important that the organization provide for continuity in 
this respect, so that what might be called the "complete 
standard" will be carried along from shift to shift and the 
gaps caused by the absence of any member of the super- 
visory force safely bridged. 

If a foreman-inspector has a department which com- 
prises several separate floors or shops, he will need an assist- 
ant in each shop. This man's duties, in addition to main- 
taining discipline, will involve a continuous checking up of 
the inspection work going on in the shop, deciding doubtful 
cases — which arise principally in the reinspection of rejected 
work — overseeing the care of gages, and attending to the 
orderly storage of work in process. Each inspection crib 
should have a working inspection boss — that is to say, one 
of the ablest inspectors working in the crib should be desig- 
nated to assume general charge of all the work going on in 
the crib. The working force in each crib will consist gen- 
erally of inspectors, counters, and in addition, especially if 
the boxes of work are heavy and if the flow of work is rapid, 
a common laborer or two. The counters are, of course, 
engaged in the work of checking up the quantity of work 
performed on operations that are not inspected, and are 
listed separately merely to indicate that this work should be 
performed at a lower rate of pay from inspection proper. 

Duties of Inspectors 

In this connection it may be noted that a misunder- 
standing sometimes arises when the employment department 



148 THE CONTROL OF QUALITY 

hires men as inspectors, and the inspection department sub- 
sequently places them in central inspection cribs where they 
may have to do more physical handling and lifting of boxes 
of work than they do inspecting. The individual thinks he 
is going to be an inspector, but finds difficulty in distinguish- 
ing between his work and that of a shop laborer. It is sug- 
gested that this difficulty may be lessened by creating the 
position of assistant inspector as an intermediate step 
between common labor and bench inspector. If the em- 
ployment department is careful to make clear to the appli- 
cant what his duties are to be, there is less chance of a 
misunderstanding later on. 

Central inspection is usually reinforced by a small group 
of floor-inspectors. These men should be of a higher grade 
than the bench inspectors in the crib, and probably higher 
even than the working foreman of the crib, since their duties 
are performed more independently. Consequently they 
should report directly to the assistant foreman in charge of 
inspection in the shop, and not to the crib foreman. 

The Chief Inspector's Staff 

It was remarked on page 144 that the chief inspector's 
staff should have no executive authority, other than that 
which accrues to them by reason of their close association 
with the chief inspector. The latter fact will naturally 
give them all the prestige their work requires. The staff 
organization should be laid out along functional lines so as 
to provide a general service for the help and guidance of the 
line executives. It must secure also, for the assistance of 
the chief inspector, an inspection of inspection, without de- 
stroying the individual responsibility or dividing the au- 
thority of the chief inspector's subordinate executives. Such 
division of authority is one of the greatest dangers in large 
organizations of combined line and staff type. 



ORGANIZATION OF INSPECTION DEPARTMENT 149 

Thus each staff assistant will be a carefully selected 
specialist, combining the work of an instructor in his line of 
work with that of assisting the chief inspector in checking 
up his assigned part of the work throughout the entire de- 
partment. The staff duties to be performed may be listed 
.as follows, with the understanding that some of them may 
be combined under one individual where the volume of work 
warrants it: 

1. Personnel matters, including the investigation of 

questions affecting pay, promotion, discharge, as- 
signment of new employees, etc. This work 
usually requires the entire time of one man. 

2. Follow-up of technical instructions from the chief 

inspector's office to the inspection force, including 
checking up the adherence to prescribed standards. 

3. Care, use, and custody of gages, including making 

sure that all gages pass through the gage-checking 
department as scheduled. 

4. Analysis of trouble reports from the foremen-in- 

spectors, especially those relating to technical 
difficulties encountered in the parts-making shops 
and in the assembling department. This work 
includes the further investigation of the reports, 
also seeing that the more important ones are 
placed before the chief inspector to bring to the 
attention of the proper authorities in the general 
factory organization. 

5. Liaison duty with the production engineer to see that 

the inspection department is collecting produc- 
tion data for him in a satisfactory manner. 

In addition, the chief inspector frequently has small 
technical matters requiring the services of a junior engineer 
to conduct the preliminary investigation. It is suggested 



150 



THE CONTROL OF QUALITY 




ORGANIZATION OF INSPECTION DEPARTMENT 151 

that such men be taken from time to time from the rank and 
file of the inspection force, or from the laboratories. This 
practice will serve to broaden the men in question, and will 
accomplish the specific purpose in hand quite as well as if 
they were permanently assigned to the staff of the chief 
inspector's ofhce. Under some conditions, as a more or less 
temporary expedient in guiding the factory toward the best 
compromise required by the commercial situation, the chief 
inspector may be given a staff assistant taken from the sales 
department. In this case the sales department may be re- 
garded as the purchaser and the sales representative as the 
purchaser's inspector. 

The Inspection Department Personnel 

Little has been said as yet about the qualities to be 
sought for in choosing men for the duties of foremen-inspec- 
tors, their assistants, and the working inspectors. The 
problem is not one of choosing the kind of men who are best 
qualified, but rather of making the best use of the men that 
are available. There is ' ' history ' ' in the statement, as more 
than one chief inspector can testify from sad experience in 
recent years. 

Some of the men who take employment in the inspection 
department have had previous experience in technical work, 
and some have not. If the experience of the former class 
has resulted in a self-sufficient knowledge, they should be 
replaced by men of the class who have no such technical 
experience, and know that they do not have it, because the 
inspectors must follow the standards set, without modifying 
them in the light of their previous experience. In other 
words, obedience to orders is the prime desideratum. 

In assigning duties in the inspection department organi- 
zation, therefore, it is necessary to place the personnel so as 
to grade the amount of discretion to be allowed in matters 



152 THE CONTROL OF QUALITY 

requiring the exercise of judgment. It might be said that 
the amount or quantity of judgment to be applied by any 
individual member of the inspection force should be de- 
creased as we go down the line from foreman-inspector to 
the inspector working in the crib. 

The Bench Inspector 

The inspector applying gages at the bench, or inspecting 
finish as to sample, should be the kind of person who has 
reasonably good eyesight and tactile sense ; but more than 
this' he must be temperamentally suited to doing exactly 
what he is told to do. This will consist in sorting the work 
he is inspecting into work that is clearly according to 
standard, work that is clearly not according to standard, 
and work about which he is doubtful, leaving the decision 
as to the latter class of work to his immediate superior. 
As stated before, this process implies reasonably definite 
standards of quality in the first place. 

The Floor-Inspector 

The floor-inspector should be of entirely different charac- 
ter. He has the important duty of first-piece inspection 
before he authorizes a machine to begin a run of work. In 
addition he may be given the right to order a machine 
stopped if the work is not to his satisfaction. This calls for 
good judgment backed up by practical experience, hence the 
floor-inspector is usually a first-class machinist, to whom the 
title and duties of inspector may make an appeal, or who 
views this work as a step in the direction of a foremanship of 
some sort — which it certainly should be. 

Salvaging Native Ability 

Practically every large inspection department possesses 
a unique characteristic, and a very happy one. It is a veri- 



ORGANIZATION OF INSPECTION DEPARTMENT 153 

table "gold mine" of men possessing unusual native ability 
and good character, but lacking experience in factory work. 
Every once in a while, and for various reasons which do not 
matter, some man decides to make a radical change in his 
work. His very lack of acquaintance with factory life may 
be the source of his desire to try it, and he presently appears 
at the factory employment office. Having no knowledge of 
machinery, he hesitates to attempt machine operation, even 
if the way is made easy for him to acquire the necessary 
skill; but the title of inspector may make a special appeal, 
both as a dignified occupation and as an opportunity to 
learn more about manufacturing methods at close range. 
This is one explanation of the presence of such men in 
the inspection department. As to where they are to be 
discovered, the answer is, obviously, at the bench, usually 
working quietly but nevertheless with their eyes open to 
what is going on around them in the shop. Unless the fore- 
man is an unusually human sort of executive, he will fail to 
see the possibilities in these subordinates. Someone higher 
up must keep an eye out for such men, and see that they are 
given the chance they hoped for when they entered the 
establishment. 

A Case in Point 

The circumstances just referred to came to my attention 
for the first time a few years ago, in the course of reorganiz- 
ing an inspection service of some 2,000 employees, where 
an excessive labor turnover in this department was con- 
sidered to be one of the primary reasons for defective con- 
trol of quality. The problem of reducing the turnover was 
attacked by direct action — the chief inspector had a personal 
talk with every man entering or leaving the department. 
The experience was somewhat arduous, but this was more 
than offset by the results, which were felt almost immediately. 



154 THE CONTROL OF QUALITY 

A certain foreman-inspector complained regularly and 
frequently that the men supplied him were " no good." The 
foreman himself was a man of long experience in the busi- 
ness, and by reason of this fact seemed unable to adjust 
himself to the necessity of training the men supplied him 
rather than expecting to find men already skilled in their 
work — a situation resulting from the war time labor condi- 
tion. Most of the men leaving his department gave every 
reason but the right one for quitting, probably in the fac- 
tory spirit of being good losers. Presently, however, a man 
appeared in the chief inspector's office on his way out. 
Character and personality were written plainly on his face. 
Under pressure he told his story, and in a detail that showed 
a keen grasp of conditions. 

Briefly, the story was this. After completing a semi- 
technical college course, he had taken a political job, and by 
an unlucky swing of the political pendulum about fifteen 
years later found himself under the necessity of seeking 
other means of supporting his family. So he turned to this 
particular factory because he had heard of possible opportu- 
nities there. It looked to him like a fresh start with good 
chances for a satisfactory career. After three months at 
the bench as an inspector he confessed that he knew little 
more about the intricacies of the business than when he 
started. What he did know, he had been forced to dig out 
by himself without encouragement from above. On the 
other hand, he knew what was basically wrong in that shop 
better than the foreman-inspector himself. 

This experience was the cause of starting a school for 
such men under an old foreman who possessed a heart as 
well as a head, and who passed on enough of his practical 
knowledge to enable his pupils to qualify as tool-setters and 
gang bosses. After this, promotion was up to the individual, 
but he was always encouraged to bring his problems back to 



ORGANIZATION OF INSPECTION DEPARTMENT 155 

his old instructor for helpful advice. The man whose case 
was just referred to became assistant superintendent of a 
large production department in about six months from the 
time when he was ready to give up in disgust and discourage- 
ment. Several other men, discovered in the same way, were 
developed into excellent foremen instead of being lost to the 
organization. 

Study the Individual 

All of which suggests that while the individual unit of 
an organization may be, in one sense, part of a machine, he 
nevertheless is a man, with all of the perfectly natural limi- 
tations and variable potentialities of a human being. I ven- 
ture to say that there is nothing in the entire work of organiz- 
ing and running the inspection department (not to mention 
the rest of the factory) that will yield so large a return, both 
in actual accomplishment and in personal satisfaction, as 
the study of the men themselves. 



CHAPTER X 

MANAGEMENT OF THE INSPECTION 
DEPARTMENT 
The Task 

The chief end to be sought in the management of the in- 
spection department is to obtain a firm control of quality 
by holding the work to definite predetermined standards; 
and to accomplish this with the maximum of economy. The 
task presents at least two essential differences from the 
management of a production department of commensurate 
size: 

i . The working force is widely scattered and the work 
unusually varied. Co-ordination is difficult. 

2. The pay of inspectors is nearly always low in propor- 
tion to their responsibilities, with attendant difficulty in 
attracting and keeping the right kind of labor. 

Co-ordination 

The first step in co-ordinating the work of the inspection 
department is to see that the chief inspector's office is lo- 
cated as nearly as may be in the center of the plant. 1 The 
inspection force is concerned with every manufacturing 
process going on in the factory and with many of the general 
service departments. It reaches into every part of the plant. 
Questions arise every hour of the day that call for settle- 
ment by personal conference with the chief inspector or some 
member of his staff. Much time and effort will be saved by 
lessening the average distance to the point of trouble. 
Furthermore it is greatly to be desired that both production 
and inspection department executives feel that the chief 

1 In the author's opinion, the same statement is true for all executive and managerial de- 
partments. See "Production as Affected by Size of Plant," by G. S. Radford, Management 
Engineering, Aug. 1921. 

156 



MANAGEMENT OF INSPECTION DEPARTMENT 157 

inspector is in as close contact with the work as they are 
themselves. The chief inspector's job is not in the front 
office, but rather in the very heart of the works. Moreover 
it is in every way a more sociable arrangement, and that is 
desirable. 

The Use of Conferences 

In co-ordinating the efforts of his own executives, the 
chief inspector will find use for all of the ordinary devices 
of good management. He will find conferences with his 
superintendents and foremen of special value. 

Incidentally the main purpose of the conferences will be 
obtained more surely if the chief inspector does not do all 
the talking. The men in the room will be brought together 
better if they come to accept the conference as an opportu- 
nity to obtain the help of several minds in working out their 
immediate and most baffling problems. The chief can 
soon develop good fellowship and a common interest in the 
work of the entire inspection department, by a little adroit 
steering. 

A conference of his immediate subordinates once a week 
will be sufficient under ordinary circumstances, but it is 
suggested that this practice be supplemented by an occa- 
sional conference with the inspection executives of each in- 
spection group, for the principal purpose of developing a 
closer personal contact and acquaintance between the sub- 
ordinate executives and the chief of their department. For 
the entire department should be in harmony with the chief's 
policies and therefore quick to react to his instructions as 
they are passed down the line. Such flexibility of control 
will be strengthened more certainly by personal acquain- 
tance and through frequent contact the personality of the 
head of the department will be reflected in the department 
as a whole. 



158 THE CONTROL OF QUALITY 

Letters of Instruction and Advice 

It will be found to be an excellent plan, in co-ordinating 
the various units, if each foreman and staff employee is 
supplied with a simple letter-size binder for keeping a file of 
department bulletins. These bulletins should be issued 
from time to time from the chief inspector's office as a quick 
means of conveying his executive instructions to the entire 
organization, defining his policies and supplying technical 
information. The book should be kept on the foreman's 
desk for the subforemen to read, and it should be the duty 
of one of the staff assistants to question the subforemen 
occasionally about the messages in the bulletins which 
specially concern their work, so as to encourage them to 
keep in touch with the plans and policies of the department. 
The scheme will not work unless it is closely followed up, 
but it can be made a most potent force in keeping men "on 
their toes" and working harmoniously, especially if the bul- 
letins or instruction notices are explained and discussed in 
conference. 

Finally, it is in the general work of helping to keep the 
entire department pulling together smoothly, that the mem- 
bers of the chief inspector's staff will justify their employ- 
ment. To make their work most effective, the chief should 
encourage them to confer with him. Whenever practicable 
they should make their headquarters in the chief's office. 

Reduction of Turnover of Inspection Force 

No matter how thoroughly standards of quality are 
specified, there will be a certain amount of incompleteness 
in the statement of them that can be filled out only from 
the accumulated experience of the inspector. Again, it re- 
quires a varying length of time for any inspector to acquire 
the technique necessary to apply a given gage with the de- 
sired accuracy and skill, or to conduct satisfactorily any 



MANAGEMENT OF INSPECTION DEPARTMENT 159 

given inspection operation. Because of these reasons it is 
important that the personnel of the inspection force be as 
permanent as that of other departments, or even more 
permanent, if standards of quality are to be prevented from 
fluctuating. This is in addition to the usual loss in quan- 
tity of work performed, due to excessive labor turnover in 
any class of work. The disparity in pay already referred to 
is a disturbing element and the turnover in a large inspec- 
tion department is likely to be unduly high in consequence. 
Obviously, the primary action to take in order to stabi- 
lize conditions is to employ people for inspection work who 
are most likely to take to it kindly. For example, the in- 
spection work is usually less strenuous than the operation of 
manufacturing machines, which indicates the employment 
of people (frequently women) who cannot stand the physical 
strain of the heavier production work, and know it. 

Provision for Promotion 

When a relatively high degree of experience and skill are 
requisite, as in the case of floor-inspectors, there should be 
assurance that the inspection force will share in promotions 
to assistant foremanships in the production departments, so 
that the inspectors have something to look forward to when 
higher vacancies are to be filled. 

Since the easier way of the direct financial incentive is 
mostly barred, resort must be had to every possible non- 
financial incentive. That is to say, in brief, that the inspec- 
tion department must be handled so that it will come to be 
recognized as an excellent place in which to work — and more 
important yet, a force that a man should be proud to belong 
to. The work can be made pleasant if the inspector is 
treated by his executives with just a little more friendliness 
and courtesy than is customary in shops. I do not mean to 
imply that his job should be made a soft one. On the con- 



160 THE CONTROL OF QUALITY 

trary, the spirit of the organization, and hence the dignity of 
the work, will be greatly enhanced by stressing the value of 
character, by cultivating a pride of achievement in terms of 
accuracy, and by a rigorous demand for personal responsi- 
bility. But all of this should be tempered by a very obvious 
interest, on the part of the chief inspector and his assistants, 
in the personal welfare and interest of everyone in the de- 
partment. If this takes only the form of an evident will- 
ingness to help the other fellow to help himself, the object 
sought will be attained. All parties gain — the executive by 
having a more contented and efficient force, and the sub- 
ordinate by having a conscious increase in satisfaction in his 
work, through the knowledge that his value to himself and 
to others is growing all the time. 

Wages 

Owing to the fact that it rarely is practicable to measure 
the work performed by inspectors, it is the general practice 
to pay them on the day-wage, or hourly wage basis. It 
frequently occurs that the inspection work must be per- 
formed in a shop where the machine operators are paid on a 
piece work or similar system based upon the quantity of 
work performed. Hence it is not unusual to find a situa- 
tion arising where ordinary machine operators are paid at 
rates considerably in excess of those paid the men who in- 
spect their work, and under such circumstances, there is 
more than the usual difficulty in keeping the inspection force 
in a contented frame of mind. 

The easiest apparent cure is to raise the wage scale for 
inspectors, but that way is rarely open, in spite of the fact 
that the inspectors perform work in many cases that is 
worth enough to warrant a higher scale. An economy in 
total cost might conceivably be attained thereby, but in 
nearly every plant, inspection is regarded as a necessary 



MANAGEMENT OF INSPECTION DEPARTMENT l6l 

but regrettable and non-productive expense. Consequently 
the chief inspector is faced with the problem of doing the 
best he can with a strictly limited pay-roll, and therefore is 
forced to use the lowest rate of wages that will keep him sup- 
plied with a grade of labor that will do. 

As a result the chief inspector and his foremen will be 
besieged with requests for raises in pay, and a relative de- 
gree of contentment can be obtained only by having a 
definite rate of promotion with graded rates of pay based 
upon length of service in combination with efficient work. 
This, I believe, has been found to be the best solution under 
the day- wage system for all kinds of work. I have seen the 
labor turnover actually decreased by the flat announcement 
that no increase in pay would be considered for sixty days, 
and this in the face of insistent demands for raises. In this 
instance, however, there had been no systematic arrange- 
ment for graded increases, so that the practice of asking for 
raises had grown up, with the net result that the granting of 
one request only served to encourage others. 

Piece Work in Inspection 

It is believed that inspectors working on small pieces 
can be paid piece work to advantage in many more cases 
than would ordinarily be supposed; but this system, obvi- 
ously, can only be used to advantage when the work war- 
rants a check inspection, or inspection of inspection by 
sampling all work after the piece working inspectors have 
gone over it. When this can be done without sacrificing 
quality, the usual economy inherent in the piece work sys- 
tem will be experienced, although the individual worker 
makes more money. Inspectors employed on piece work, 
however, must be penalized strictly by non-payment for any 
boxes of work found to contain defective parts, and less 
heavily for the rejection of good parts. 



1 62 THE CONTROL OF QUALITY 

Working Hours 

Another potential source of discontent arises from the 
fact that at least a part of the inspection force will need to 
be on hand both before and after the regular working hours. 
It is especially important that the inspection cribs be ready 
to issue work before the beginning of work in the shop — 
sufficiently early, indeed, to make sure that all machine 
operators are supplied with work well ahead of time. Other- 
wise the production force have a valid cause for complaining 
that they are delayed in getting to work promptly. Then 
again, it is often desirable that work turned in at quitting 
time should be inspected at once. When choke-points 
occur this may be imperative. The suggestion is offered 
that much unnecessary hard feeling can be stopped by a 
definite understanding, at the time of employment, that the 
working hours of inspectors will be staggered a little out of 
phase with the regular shop working hours. The total time 
can be adjusted by allowing a longer time for lunch and by 
a reasonable leniency in days off. The time outside of 
regular hours need not exceed 15 minutes in most cases, so 
that adjustments of total time are not difficult. Needless 
to say, overtime should be avoided with care, as both costly 
and conducive to the creation of additional and needless 
overtime. 

The Cost of Inspection 

Most chief inspectors will agree that the average fore- 
man-inspector, by reason of his being a foreman-inspector 
and concurrently with his assumption of that duty, at once 
develops an unusual ability to ask for more inspectors, and 
for better inspectors, and for more gages. Now as all of 
these things cost money, which is a relatively rare commodity 
in so far as the chief inspector's disbursements are permitted 
to go, some other way out must be found. For example, 



MANAGEMENT OF INSPECTION DEPARTMENT 



163 



the foreman may be shown that more men does not neces- 
sarily mean a corresponding increase in the amount of work 
performed. Thus in the curve shown in Figure 37 — in which 
the abscissae represent the total number of men in the work- 
ing force, and the ordinates represent the total amount of 
work performed — it is not unnatural to assume that output 
will increase in direct proportion to the number of people 



S D 



No. of Men 
Figure 37. Curve of Output and Number of Men 

engaged in the work, as shown by the line OA — the more 
men, the greater the total output. 

As a matter of fact, a little consideration will show that 
the curve OBC is more nearly true for any given job, for the 
reason that a point, B, is soon reached where additional 
help only interferes with the people already at work, until 
at C the shop is so crowded that no one can move, and the 
output returns to zero again. Hence it follows that for any 
given output, OD, there are two limiting numbers of men, 
DE and DF. It is the painful lot of the inspection depart- 



1 64 THE CONTROL OF QUALITY 

ment to work a little inside of the number of men indicated 
by the point E. This may not be entirely convincing to 
your foreman, but it at least shows them what they are up 
against in asking for more men. 

Teaching Inspectors 

Rather than engaging more men, therefore, it is a mat- 
ter of increasing the efficiency of the allowable force and 
here it may be noted as a fortunate circumstance that in- 
spection work lends itself readily to very marked economies 
in the way of greater output per man, through the applica- 
tion of many of the devices of modern methods of manage- 
ment. This is especially true of bench inspection, under 
the conditions of central inspection. The device of greatest 
utility is a carefully planned use of sampling, insuring that 
no more work is done than is necessary. Next comes the 
matter of instruction in the work of inspection, to see that 
each inspector knows just what he is trying to do, and the 
quickest and easiest way to do it. There are so many 
operations in inspection work which appear very simple, 
that there is a strong tendency to show a new employee 
what he has to do in a very casual and general sort of way 
and then leave him to his own devices. The application of 
a gage or two, or a viewing for surface finish, appears to be 
transparently easy, but the mental attitude that regards 
any piece of work as simple is a danger signal. It should 
be borne constantly in mind that time and motion study 
began with handling pig iron and shoveling earth. It is not 
unlikely, in fact, that the most striking economies are to be 
realized in the most simple operations. 

The instruction of inspectors is a staff job — that is, it 
should be a staff job if the best results are to be obtained. 
Perhaps this conclusion flows from the proverbial truth that 
work which is left to everybody is rarely done right. 



MANAGEMENT OF INSPECTION DEPARTMENT 165 

Combine Instruction with Staff Supervision 

The instruction should be combined with the work of 
one of the technical men on the chief inspector's staff, as it 
fits in well with a critical examination of each inspection 
point taken seriatim and somewhat as follows: 

1. Is the measuring device, gage, or what-not, such 

that true results can be obtained? 

2. Is the gage being applied so as to obtain true results? 

3. Is the work being done in a way to secure the great- 

est economy of inspection? 

The first two questions are vital, naturally, since money 
spent upon inspection is worse than wasted if the results are 
not close to the truth. The third question opens up the 
whole field of possible increase of efficiency. Frequently, 
in fact, the most cursory use of motion study reveals large 
possibilities for saving time in inspection, especially if the 
inspector considers himself under the necessity of hurrying. 
The most frequent loss arises from improper placing of the 
boxes of work, so that unnecessary and overcrossing motions 
are made. Then there are the losses that arise from awk- 
ward posture and clumsy holding of the gage. It sometimes 
happens that a separate support for the gage will help mat- 
ters by leaving free both of the inspector's hands. In this 
case attention should be given to seeing that the support is 
flexible enough to permit automatic adjustment of a close 
limit gage to the work. 

A large saving can be secured through spreading the 
message of careful handling of both work and gages. Pre- 
cision instruments and fine work call for a certain amount 
of gentleness, of the sort that the late A. J. Corbesier, the 
honored fencing master at Annapolis, referred to when he 
said, "Hold your foil as you would a bird — firmly, so it will 
not escape; gently, so it will not be hurt." 



1 66 THE CONTROL OF QUALITY 

I recall an experience in a munition plant, where a room 
full of foreign help was engaged in the inspection of high- 
grade work. The gages were applied with such enthusiasm, 
and highly finished parts were thrown into tote boxes with 
such vigor that the anvil chorus would not have had a chance 
to be heard. The ordinary bench inspector or machine 
operator in our larger factories will easily fall into almost as 
bad habits unless he is cautioned continually. 

Unskilled Help in Inspection 

Turning now to one of the greatest economies in inspec- 
tion, especially in central inspection as previously stated ; it 
is not necessary (except in certain kinds of floor-inspection) 
to have a personnel already skilled in the work of inspecting. 
In fact it is quite inadvisable to employ such people when 
the object is to limit the use of judgment and to hold to a 
close standard. But the employment of unskilled help 
again indicates the necessity of providing adequate instruc- 
tion, not alone by teaching, which always should be a large 
factor in management, but also by providing accessible ref- 
erence data, such as samples, large-scale drawings with 
gaging points distinctly marked, gage instruction cards, and 
so on. It should not be necessary to mention, except for 
completeness, how important it is to begin this educational 
work as soon as the new inspector is employed. There are 
obvious advantages in "catching them young." The work 
will be done more certainly, and probably better and quicker, 
if it is followed up by a staff assistant. 

Female Labor for Inspection Work 

In speaking of the use of unskilled labor as a measure of 
economy in inspection, the question of using female labor 
deserves serious consideration. In fact, if female labor is 
carefully selected with reference to the adaptability of the 



MANAGEMENT OF INSPECTION DEPARTMENT 167 




Figure 38. Prestwich Fluid Gage as Used to Inspect Piston Pins 

Diameter held to within 0.0002 inch — Packard Motor Car Company. 



1 68 THE CONTROL OF QUALITY 

individual to the class of work involved, it will be found that 
women are able to do many more kinds of inspection work 
than might be supposed, also that they almost invariably 
perform it better than men. A higher grade of tactile^ense 
and skill can be secured for the same investment, together 
with a stricter compliance with instructions in the matter of 
holding to standard. The advantage to be gained in 
greater contentment of the inspection force alone, makes the 
employment of women highly desirable whenever possible. 

It is realized that many factory executives hesitate to 
introduce women into the inspection department in shops 
where none but men are employed at the machines, and this 
for reasons quite apart from their suitability for such inspec- 
tion work. It may be stated as a fact, however, that the 
feeling is not warranted if proper measures are taken at the 
start to maintain discipline ; for the presence of women may 
be made to secure an elevation of the entire tone of the shop. 
To do this requires that the subordinate inspection bosses 
be chosen from among the most dignified inspectors and that 
they be duly impressed with the importance of their work. 
It should be made a fixed rule also, that questions affecting 
inspection be taken up by the production bosses with the 
male foreman only. 

In a large factory employing at the time none but men 
in the shops, female help to the number of several hundred 
were introduced into the inspection department in the en- 
deavor to stabilize labor turnover in the department, as well 
as to secure better control of the technique of inspection. 
Because of the class of labor in the plant, the management 
realized that matters might arise which would be reported to 
them more certainly, and perhaps more easily and gracefully, 
if the women could carry their troubles to a woman rather 
than to a man. It was recognized, besides, that a high 
standard of character in the inspection department was 



MANAGEMENT OF INSPECTION DEPARTMENT 169 

worth a great deal in controlling the quality of the factory 
output. With this in mind, one of the secretaries in the 
main office, who had been a working girl and who combined 
rare judgment with a very human sympathy for her asso- 
ciates, was asked to take the time to become acquainted 
with at least one or two girls in each inspection group. 1 ne 
plan proved to be an unqualified success, although it resulted 
in the dismissal of a foreman or two, and a few of the inspec- 
tion force, very shortly after the facts began to come in and 
investigations were made. It was not long, however, before 
that particular plant achieved the reputation among work- 
ing people of being the safest factory in the state to which to 
send their daughters for employment. 

Women as inspectors will be found to work faster than 
men, especially if their strength is conserved by providing 
men to do the heavier work of lifting and moving tote boxes. 
The amount saved is sufficient to pay for the greater com- 
forts in the way of chairs, recreation and rest rooms, and 
other conveniences, that must be provided for women. It 
should be remembered, however, that women inspectors 
should be required to adapt their dress to secure personal 
safety, by wearing caps and suitably protected sleeves, as 
in the case of female machine operators; for even women 
inspectors are occasionally passing near machinery in 
motion. 

Women Inspectors on Heavy Work 

From the technical standpoint, there are many kinds of 
work not ordinarily inspected by women which could be so 
handled to advantage, even in the case of comparatively 
heavy pieces. This requires that the individual be chosen 
for the job and given a preliminary course of training. The 
inspection of the interior of rifle barrels has been performed 
by women to great advantage, although it is technically 



170 THE CONTROL OF QUALITY 

difficult and the physical work of holding them up to the 
light is tedious, to say the least. In the case I have in mind, 
the inspectors were chosen from among a number of obvi- 
ously robust and sturdy individuals, whose eyesight meas- 
ured very nearly perfect. They were then instructed in the 
art by an expert foreman who believed that women could be 
taught to do the work. It took ten days to graduate them, 
and it only remains to be stated that they developed a pro- 
ficiency that at first set too high a standard. It would, in 
fact, have tied up production, if prompt measures had not 
been taken to reinspect their rejects, until they could be 
taught to hold to a more reasonably commercial standard. 
And in spite of this experience the scheme was nearly wrecked 
by their inspection foreman (a man of long experience and 
great skill in the business), who stubbornly refused to be- 
lieve that women could learn, in so short a time, work re- 
quiring such skill. From this fact the reason may be de- 
duced for emphasizing certain words in this paragraph. It 
may possibly suggest in addition, that there is more than a 
modicum of "bunk" about many skilled operations, so- 
called, as is rapidly discovered when the problem of con- 
trolling them is approached in a truly scientific manner. 

Morale 

No treatment of the management of the inspection de- 
partment should close without stressing the special value 
of a high morale. Just as the precision of measuring instru- 
ments is fundamental in determining the degree of mechani- 
cal accuracy that may be attained, so must fidelity to truth 
be developed in the inspection force, to secure the predeter- 
mined standard of quality that is desired. Thus character 
is the first desideratum, and as a necessary element of it, 
impartiality, thoroughness, and accuracy in developing the 
real facts, and courage in bringing them to light. The chief 



MANAGEMENT OF INSPECTION DEPARTMENT 1 71 

inspector must train his people to secure this result; and 
then, lest he lose the advantage, he must support them when 
they are right, and must in his turn be supported by his 
superiors in the management. Concurrently, the inspec- 
tion force should be disciplined to a strict obedience in 
carrying out the chief's instructions, if for no other reason 
than to secure a quick flexibility and certainty of control in 
developing the standards of quality, with freedom from dis- 
turbing influences arising outside of the inspection depart- 
ment. 

The presence of this same discipline, administered always 
with personal courtesy, will build up the individual's sense 
of the value of his work to the entire organization; and with 
the resulting realization of personal dignity and knowledge 
of trust, there will come a feeling of responsibility and pride 
in the work of the whole department — that is to say, an 
esprit de corps. 



CHAPTER XI 
INSPECTION IN PRACTICE 

Type Varies with Individual Factory 

The development of a philosophy of inspection requires 
that its principles be stated somewhat in the form of abstract 
generalizations. It is believed, as has been stated, that 
these principles are of much wider application than is gen- 
erally appreciated and that industry would benefit greatly 
if they were followed much more closely in practice. It is 
equally true, however, that the translation of these prin- 
ciples into action, as has been pointed out in several in- 
stances, requires that they be interpreted with a leaven of 
common sense, and applied in the form of whatever adap- 
tation is economically most suitable for the particular case 
involved. 

Each manufacturing enterprise has its own peculiar con- 
ditions to meet, and the arbitrary introduction of a fixed 
system of any sort, without careful and intelligent modifica- 
tion, is fraught with grave dangers. "What is one man's 
meat is another's poison." 

If the management is critically introspective, so to speak, 
the way in which inspection is organized and applied is likely 
to be well suited to the needs of the factory. Hence the 
value of studying the inspection methods of well-established 
industries, whose successful operation may be taken for 
granted. Such study is the purpose of the present chapter. 
As an introduction thereto the various modifying consid- 
erations which are involved in special cases may now be 
assembled. 

172 



INSPECTION IN PRACTICE 173 

When to Use Extensive Inspection 

Briefly stated, the most extensive and complex use of 
inspection is desirable when : 

1. The product demands frequent and thorough in- 

spection, as when great accuracy is required. 

2. When models are changed with frequency, as in a 

swiftly advancing art. 

3. When labor is unskilled or rapidly changing. 

4. When quality standards are being raised. 

5. When considerable judgment must be used because 

standards are being shifted or have not been re- 
duced to a definitely measurable basis. 

Each of these cases may apply separately but when they 
are cumulative, as in the case of unskilled labor working in 
an industry that is advancing swiftly, the use of a much 
more intensive form of inspection is indicated. 

On the other hand, if the product is highly standardized 
and if the workers are skilled mechanics well acquainted 
with the requirements of the work, then inspection may be 
greatly reduced. In fact, if the work is performed under 
these conditions and on so small a scale that the manage- 
ment is able to devote considerable attention to the details 
of the business, the need for inspection almost disappears. 
Cases of the latter sort are very rare, however, and are not 
worth considering except as exemplifying the extreme or 
limiting situation. 

The following examples have been chosen from a number 
of industries with the idea of presenting in brief form certain 
general features of inspection methods which are typical. 

Inspection in Automobile Plants 

In looking for a good example of inspection as practiced 
in its highest development, there is no better place to turn 



174 



THE CONTROL OF QUALITY 



than to the automobile factories. The evolution of auto- 
mobile design and manufacture is one of the great romances 
of modern industry. For reasons that need no mention, it 
has made tremendous demands upon every department of 
engineering science and the technical arts, in order that 
ways and means for meeting its requirements might be de- 
vised. It has made it necessary to create a new school of 
machine tool design, to carry tool-room precision into the 
ordinary fabricating shops, and to install every reasonable 
safeguard for controlling quality. 

The Packard Inspection Service 

Inspection in the factory of the Packard Motor Car Com- 
pany l has been developed to a point that is best illustrated 
by the organization chart shown in Figure 39. The chief 



























FACTORY 
EXECUTIVE STAFF 








1 








CHIEF INSPECTOR 






























DIVISION SUPT. 
INSPECTION 




ALTERATION SUPT. 








1 












1 




1 




t 




1 










FOREMAN 
FORO.E INSPECTION 




FOREMAN 

FOUNDRY INSPECTION 




FOREMAN 

OUTSIDE 

FINISHED MATERIAL 




FOREMAN 
INSIDE INSPECTION 




FOREMAN 

R0U6H STOCK 

INSPECTION 






1 




1 








1 




| 






INSPECTORS 




INSPECTORS 




INSPECTORS 




INSPECTORS 




INSPECTORS 































Figure 39. Inspection Organization Chart — Packard Motor Car Company 

inspector is responsible to the factory executive staff, com- 
posed of the vice-president of manufacturing, the factory 
manager, the assistant factory manager, and the general 

1 The author is indebted to D. G. Stanbrough, General Superintendent of the Packard 
Motor Car Company, for his courtesy in furnishing information relative to Packard inspection 
practice and precision methods. 



INSPECTION IN PRACTICE 175 

superintendent. The chief inspector is responsible for 
proper and efficient inspection throughout the inspection 
organization, in accordance with standards set by the fac- 
tory management. 

Directly under the chief inspector is an inspection super- 
intendent for each of the main divisions of the business, 
namely, carriage, truck, and service. Each of these divi- 
sions is further subdivided into three departments : outside 
finished material inspection, inside inspection, and rough 
stock inspection, with a foreman in charge of each depart- 
ment to whom the individual inspectors report. In addi- 
tion, there is an alteration superintendent, also responsible 
to the chief inspector, whose duty is to see that alterations in 
the dimensions or in the design of parts are properly put 
through in the factory with the minimum of interference. 

Both floor-inspection and centralized inspection are in 
use. Large parts, such as cylinders, crank cases, etc., are 
inspected on the floor near the machines, since manufac- 
turing facilities are so arranged as to permit it conveniently. 
Small parts, however, are removed to the department in- 
spection cribs for inspection. When a workman machines 
the first piece on a job, he is required to submit it to the 
foreman or the job-setter. If the piece is done correctly, 
the foreman or job-setter OK's the workman's time slip 
and he goes ahead with the job. If the operation is not 
done correctly, the foreman shows the workman how to do 
the operation, and the time slip is not signed until the piece 
is finished correctly. 

Final inspection of each individual piece is maintained 
on the following parts: heat treated parts and parts that 
are held to close limits, such as cylinders, pistons, piston- 
pins, crank cases, transmission parts, gears, steering 
knuckles, etc. Ordinary small parts such as screws, nuts, 
bolts, washers, etc., are subjected to a percentage inspection. 



176 



THE CONTROL OF QUALITY 



The disposition of rejected parts is rigorously controlled. 
Reference to Figure 40 shows this in detail. While the 
production department may be consulted by the chief in- 



N? 


14G099 


DEFECTIVE STOCK TAG 1 


DATE 


DIPT. FOUND IN 


£eI 


PIECE NO 


I0B SEI'H CHGB. 


DISPOSITION DATE 


ORIS. OEPT. 


jES 


OEPT CHDD. 


APPCT ON TAO NO 


OPER. OEP. 


"e T no°" 


QUANTITY OEP 


:ctive 


NAME 


Pl. 


• CRAP 




zz: 


rVp^e 


DEFECTS 









ACCEPT 


..««,.. 








PINISHEO 




FORI. 


PAIH INSTRUCTIONS SEE BACK OP NO. 1 COPT 








1 




1 




SUPPLIER 



Figure 40. (a) Inspector's Tag Disposing of Work (face) — Packard Motor 

Car Company 



INSTRUCTIONS FOR REPAIR 


DEPT 


OPERATION 






















Form 1; !0I£0M4 20 - x »a co »o» 



Figure 40. (b) Inspector's Tag Disposing of Work (reverse) 

spector, the fact remains that no piece once rejected can be 
disposed of except in accordance with instructions issued by 
the chief inspector in person. 

The foregoing pertains to the methods of handling in- 



INSPECTION IN PRACTICE 1 77 

spection on forgings, castings, semifinished and finished 
pieces. In addition to this, there is a metallurgical and 
chemical department for the usual analyses of iron and steel. 
This department, however, is separate from the regular in- 
spection organization and is in charge of the chief metal- 
lurgist, who is responsible to the factory executive staff. 
The chief metallurgist also prescribes the requisite charac- 
teristics for heat treated parts, although the actual work of 
inspection of these parts is carried out through the regular 
inspection organization. 

Operating inspection on finished vehicles is also a sepa- 
rate function in charge of the operating manager who is re- 
sponsible directly to the president. 

In addition to all of the above, the quality of the product 
is further insured by a supervisor of quality (reporting to 
the factory executive staff) whose function is to check the 
work of the inspection organization. The method of the 
supervisor of quality is to have his men take a complete 
unit at random, which is then disassembled and checked up 
in detail by his men. 

Inspectors are paid day work, which is the almost uni- 
versal practice. With a working force of 9,000 men, 500 
inspectors were employed. It should be noted, however, in 
connection with any data of this sort, that the proportion of 
workers must vary considerably from time to time, depend- 
ing upon the situation of the work and the number of work- 
men employed. Consequently, the figures that are given 
relative to the number of inspectors for any given working 
force must be considered as applying merely to a particular 
situation. 

In its general features the above outline is believed to be 

typical of the best automobile inspection practice, although 

there are naturally a number of variations from factory to 

factory. The proportion of workers to inspectors, for ex- 

12 



178 THE CONTROL OF QUALITY 

ample, varies all the way from 1 inspector to 10 workers, up 
to 1 inspector to 30 workers. 

An Example of Former Practice 

By way of contrast with the above, it may be of interest 
to compare the inspection methods in use several years ago 
in a plant which at that time was fairly prominent as the 
maker of a high-grade car. In this factory the chief inspec- 
tor reported to the chief engineer in matters affecting ma- 
terial organization and the holding of the work to drawing 
dimensions. He was responsible to the superintendent for 
the routing and movement of all work in process. 

The inspection department organization consisted of a 
chief inspector, an assistant chief inspector, department- 
inspectors, floor-inspectors, and inspectors. The depart- 
ment-inspector had charge of all inspection in his depart- 
ment and was responsible for the quality of the work and 
the discipline of his force. There were in general 2 floor- 
inspectors for every 150 operators and their duty was to 
inspect all work in process at least four or five times a day. 
They were required to check each new set-up before work 
could start, after which the machine operator was held 
responsible for all defective work. 

The floor-inspectors inspected and had moved to the 
various operations, all large pieces of work, such as crank- 
shafts, axles, radius-rods, drive-shafts, and fly-wheels. These 
parts were moved into the central inspection room only 
when finished or at the time of being moved from one de- 
partment to another, in order to fix departmental responsi- 
bilities. 

Work requiring skilled mechanics, such as grinding 
crank-shafts, cam-shafts, cylinders, pistons, piston-rings, 
gear-cutting and grinding, boring of crank cases and trans- 
mission cases, was not considered to require floor-inspection. 



INSPECTION IN PRACTICE 



179 




180 THE CONTROL OF QUALITY 

The floor-inspectors were usually expert machinists receiving 
(prior to 1914) about 70 cents an hour, and as an incentive 
were usually next in line for promotion to assistant foreman 
and foreman. 

The amount of inspection given to each lot of pieces 
depended upon the quality of the lot as determined by the 
first few pieces inspected. That is to say, if the first few 
pieces were good, the inspector examined about 25 per cent 
of the lot. If any were bad he would then inspect the entire 
lot. In each case he then counted the work and credited 
the operator with the number of pieces passed. 

For a force of 1,500 operators there were 40 bench- 
inspectors, 8 floor-inspectors, 2 inspectors for commercial 
work, 1 inspector for forgings and castings, and 1 inspector 
on the scleroscope test. All of these men were paid on the 
hourly basis, bench inspectors receiving from 50 to 65 cents 
per hour. The drawing was the only standard allowed, 
close dimensions being stated with the limits given in detail. 
Limits of plus or minus 0.0 10 inch were allowed on all di- 
mensions which were stated in fractions. The standard of 
finish was marked on the drawing to denote the points to be 
finished, the allowance for grinding (say 0.010 inch), and 
the surfaces to be disc-ground or spot-faced, and no depar- 
ture was allowed from the above without the written au- 
thority of the chief inspector. It is of interest to note that 
the company, being responsible only to themselves for their 
standards, had permitted it to become the accepted practice 
in the shops to shift the standards of workmanship and ma- 
terial to suit the urgency of the demand for parts, keeping in 
mind the ability of the assembling department to use them 
without increasing the cost too much — this from the state- 
ment of the chief inspector to the writer. 

In the routing of work, in accordance with operation 
sheets furnished to the inspector, the work was accompanied 



INSPECTION IN PRACTICE l8l 

by a route card, or traveler, which stated the part number, 
order number, and quantity. This card moved with the 
work from raw material to finished stock. When an opera- 
tor finished his operation, he took the card to his foreman, 
who then gave it to the time-keeper. The time-keeper then 
made out an inspection ticket in triplicate, keeping one copy 
himself. The remaining two went to the inspection depart- 
ment where the inspector filled out the quantity accepted or 
rejected. Of these two copies one was sent to the pay de- 
partment and the other returned to the workman. The 
inspector then made out a card, ordering the material out 
of the inspection department and delivered by the trucker to 
the next operation. 

Machine Tool Industry 

In the manufacture of machine tools, the organization 
and methods of inspection do not differ widely from those 
employed in the best run automobile factories. As might 
be expected, however, the same degree of refinement has not 
been reached, although there is evidence that inspection 
methods are being overhauled rather carefully in several of 
the machine tool making factories, as a result of their experi- 
ence in the war. The ratio of inspectors to workers varies 
all the way from I to 30 for ordinary machine tool work, 
up to 1 to 15 in the case of small tools. Inspectors are paid 
on an hourly basis. In many plants central inspection, floor- 
inspection, and first-piece inspection are all in use together. 

The most marked deviation in inspection organization 
is in the relation of the inspection department to the rest 
of the organization. In the Pratt and Whitney Company, 
for example, the chief inspector reports directly to the works 
manager, but this is by no means the general practice else- 
where in the industry. In some factories the chief inspector 
reports to the engineering department. In others he re- 



1 82 THE CONTROL OF QUALITY 

ports to the factory superintendent. These latter prac- 
tices are of interest as indicating the results of an inherited 
system. 

Small Precision Work 

Inspection methods have reached a high development 
in many plants which are engaged in the manufacture of 
small high-grade articles. For example, in the Elgin Na- 
tional Watch Company's 2 plant the inspection work is per- 
formed in a central inspection room or space, generally set 
off at the end of each department. Each piece produced is 
submitted to ioo per cent inspection. Out of a total work- 
ing force of 3,500 the ratio of inspectors to workers averages 
1 to 10. All inspectors are paid by the day. Each main 
factory division has its own inspection department with a 
chief inspector in general charge. 

At the Weston Electrical Instrument Company's 3 plant 
at Waverly Park, Newark, central inspection is in use, but is 
reinforced for certain classes of work by so-called "floating 
inspectors" who move through the various departments 
where inspection at the machine or at the completion of the 
process seems to be advisable. In general, first-piece in- 
spection is held to be a part of the responsibility of the depart- 
ment in which the work is done, and is not covered by the 
inspection department except in special cases. Most of the 
work is arranged in departments — -the milling department, 
the drilling department, etc., but no work is allowed to pass 
from one department to another without first passing 
through the hands of the inspection department. 

The ratio of inspectors to workers averages about 1 to 
10, and inspectors are paid on an hourly basis. 

Every piece of the completed product, that is to say 



2 From data furnished by DeForest Hulburd, second Vice-President. 

3 Courtesy of Edw. F. Weston, second Vice-President. 



INSPECTION IN PRACTICE 



183 




Figure 42. Inspection of Time Fuse Parts 
War work of American Locomotive Company. 



1 84 THE CONTROL OF QUALITY 

every instrument, undergoes several final inspections. The 
subassemblies and parts used in the production of Weston 
instruments are subject to individual inspection. The only 
exception is in the matter of unimportant parts (such as or- 
dinary screws) which are inspected by sampling. 

The chief inspector is responsible directly to the general 
superintendent, and is assisted by a foreman and subf ore- 
men, each subforeman controlling from 3 to 10 inspectors, 
according to the nature of the work. 

General Machine Shop and Foundry Practice 

In industries whose work requires medium and heavy 
foundry work, forgings and their machining, the inspection 
department usually is more loosely organized, although in 
highly standardized businesses of this sort, such as the man- 
ufacture of power transmission machinery, it is usual to find 
greater refinements in use, with a chief inspector reporting 
directly to the management. Most of the work is inspected 
on the floor, as a matter of necessity, but final inspection is 
not infrequently performed in a separate department. In- 
spectors are paid universally on an hourly rate. The ratio 
of inspectors to producers is as low as 1 to 50. 

Special Cases 

The inspection methods in use in the manufacture of a 
continuous product, such as paper or textiles, requires in- 
dividual treatment, depending considerably on the grade of 
the product. The general principles, as set forth for inter- 
changeable manufacturing, are the same, but different 
methods are necessary. All such work should be regarded 
as an assembling proposition, with various preparatory 
operations for the raw material and with appropriate finish- 
ing operations after the materials have been brought together 
in the goods. Errors are bound to occur and are almost 



INSPECTION IN PRACTICE 



185 



always worked into the product in such a way as to defy 
their correction. Consequently, inspection at the sources of 
greatest error has an added value in checking undue loss. 
Inspectors of high caliber are required, moreover, because 
apparently insignificant 
matters in the earlier 
stages of manufacture 
are likely to have a seri- 
ous effect upon later 
processes. The in- 
spector thus requires a 
wide knowledge of the 
technicalities of the 
business as a whole. 

An interesting vari- 
ation in the method of 
inspection is occasion- 
ally desirable for con- 
tinuous processing — if 
the workman is paid a 
bonus for quality (and 
consequently knows 
that the defective work 
will cost him money), 
he automatically be- 
comes an inspector of 
work performed on the 

material before it reaches him. In fact, it may be a desir- 
able feature in any such scheme of quality control to re- 
quire each operator to make a list of the defects he finds 
in the work as it reaches him, and, where practicable, to 
report the same before starting his own machine. 

There is another class of inspection work which has not 
been touched upon heretofore because of its very special 




Figure 43. Perch for Inspecting Textile 
Fabrics — The Shelton Looms 



186 THE CONTROL OF QUALITY 

nature. It is to be found in places where a volume of mail 
orders are packed, and in similar operations which are more 
in the nature of checking. For example, in the Charles- 
William . Stores 4 at a time when a force of about 500 
girls was employed in packing orders for shipment, the 
orders ran in about the general proportion of 300 freight, 
3,000 express, and 30,000 parcels post. Obviously, it was 
necessary to have some sort of check on the packing, 
although it was equally true that the inspection of this 
packing could not be carried very far without duplicating 
the work of the packers. Satisfactory results were obtained 
by the employment of 30 girls as inspectors, with a man- 
ager or chief inspector. Arrangements were made to carry 
the parcels through the inspection department on two 36- 
inch belt conveyors. The inspection operation was per- 
formed by sampling ; that is to say, an inspector would take 
a package from the belt, get the papers in the case, and 
check the order as filled and packed. 

Ratio of Inspectors to Workers 

As has been stated before, any figures giving the num- 
ber of inspectors required, in proportion to the working 
force, must be accepted with reservations based upon condi- 
tions surrounding the work at the time. Consequently, 
such figures can be used only as a general guide. As a mat- 
ter of convenience, the following table summarizes the data 
assembled from a number of industries : 

Ratio of Inspectors to 
Industry Workers 

Ball bearings i to 4 or 5 

Small and very precise interchangeable parts 1 to 8 or 10 

Automobiles, high-grade close work 1 to 10, up to 1 to 20 

Simpler automobile work 1 to 20, up to 1 to 40 

Machine tools 1 to 15, up to 1 to 40 

Foundry and general machine shop 1 to 50 

4 Under the organization and methods developed by its president, G. H. Eiswald. 



CHAPTER XII 

QUALITY CONTROL IN PRACTICE 

Complexity of the Quality Problem 

Inspection is only a part, although a very important 
part, of the wide and important subject of the control of 
quality. As has already been pointed out, an analysis of 
successful industries will show that these manufacturing 
activities comprise three essential branches or stages : 

i . Planning or Engineering — the determination in con- 
siderable detail, of what is to be made and how it 
is to be made, before work is begun. 

2. Production — the economical application of suitable 

manufacturing processes whose output is con- 
trollable to uniform standards of quality. 

3. Inspection — the comparison of the work as produced 

with the predetermined standards of quality, and 
the filtering of unsatisfactory work out of the line 
of flow of work in process. 

The determination of what makes an enterprise success- 
ful is a difficult matter in any case. Some things help, 
others hinder, and some are merely carried along without 
affecting the issue either way. Not infrequently success 
results from a combination of circumstances which are 
merely opportune, and vice versa. The resulting mixture of 
causes is so complex that it is hard to analyze. If, however, 
we approach the matter from the negative viewpoint, it is 
simpler to determine what the basic causes of success really 
are. The test in this case is: What are the things whose 
wow-observance will result in failure? As indicated above, 

187 



188 THE CONTROL OF QUALITY 

it is believed that a very small oversight in any one of the 
three essential branches of planning, production, and inspec- 
tion may be disastrous ; while the same thing cannot be said 
with equal truth of the other branches of factory endeavor. 

By the above test then, we should expect to find un- 
usually successful industrial enterprises accompanied by a 
close attention to planning, production, and inspection. 
The war furnished a number of examples which illustrate 
the above in a conspicuous way, both by direct and by nega- 
tive proof. Unfortunately, however, everybody was so 
busy at the time that the most valuable lessons to be gained 
from war time experience were missed, except by the people 
who came in actual contact with the industries in question. 
This is doubly unfortunate because the conditions were 
especially good for proving in a very intensive way the 
truth or untruth of the methods used. 

It is, of course, difficult to choose typical examples from 
such a quantity as are available, but the war work of the 
American Locomotive Company, the Lincoln Motor Com- 
pany, and the Remington Arms of Delaware may be selec- 
ted as illustrating strikingly the points made throughout 
this book. 

The Shell Contracts of the American Locomotive Company 

Early in 191 5, the American Locomotive Company 
undertook the manufacture of shrapnel and high explosive 
shells for the British government. The work was carried 
on under the direction of Vice-President C. K. Lassiter (in 
charge of manufacturing) . The excellence and importance 
of this accomplishment are not generally known. Such 
results, however, might have been expected of one who 
already had an enviable record as a designer of highly effi- 
cient machine tools, and as a production executive. As will 
be observed from the accompanying illustrations, Mr. Las- 



QUALITY CONTROL IN PRACTICE 



189 



siter's methods are characterized by directness, simplicity, 
and effectiveness— in short, by that absence of frills which 
denotes a genius for making things. 

In order that the magnitude of the undertaking may be 
appreciated (for it shortly grew to huge proportions), the 
following summary of the work done by the American Lo- 
comotive Company and its associated shops is of interest : 

Manufactured complete, loaded 3. 3-in. Shrapnel. 2,500,000 

" 3.3 " H. E 2,500,000 

not loaded 4 . 5 
11 « 6 



9.2 



H. E 1,468,000 

H. E 1,468,000 

H. E 300,000 

H. E 125,000 



Extra cartridge cases, complete 3.3 " 3,886,000 



4-5 



1,147,000 



" time fuses, complete, loaded 3,200,000 

" shell forgings — various sizes 2,733,700 

During the last nine months of the undertaking this tidy 
little job reached an average total daily output of 25,000 tons, 
and employed 40,000 men. The average daily output of 
cartridge cases alone was 58,000; while of 3.3-inch shrapnel 
and H. E. shells it was 40,000. To accomplish these results 
with an organization unacquainted with the work, however 
skilled it might be in other lines, certainly would indicate a 
thorough grasp of the fundamentals of manufacturing. 

Beginning the Work 

The first order undertaken was for 1,250,000 3.3-inch 
18 pdr. shrapnel, and a like number of 3.3-inch high explo- 
sive shell. Not one of these was rejected after delivery. Let 
us now see how the thing was done, beginning with the car- 
tridge case, which is the same for both shrapnel and H. E. 
shell. 

At the outset it should be noted that the contract pro- 
vided only an outline plan without tolerances or limits. 
The first step took the form of a visit to the Quebec Arsenal, 



190 THE CONTROL OF QUALITY 

where inquiries were made as to what these cases should be 
like. In other words, Mr. Lassiter first endeavored to de- 
termine what was wanted, in detail ; in fact, he frankly stated 
that he and his associates approached the work as novices. 
As a special result of this visit, two sample cartridge cases 
which were satisfactory were obtained and brought back to 
New York. These samples were then sawed in two, and the 
hardness determined by careful and extended measurements 
with the scleroscope. Dies were designed and a set of tools 
made to produce the case from blank to finish, special atten- 
tion being paid to see that the drawing processes were de- 
veloped to secure the necessary coining at the points where 
extra hardness was required. Tolerances and limits were 
then worked out. 

As an example of the processing, the annealing furnaces 
were of the oil, overtired, perforated roof type. In order to 
avoid scale, superheated steam was introduced, at a suffi- 
ciently high temperature to permit uniform control. 

Limit gages and ioo per cent inspection were provided 
for all operations from rough blanks to finished cases. All 
work rejected by either the company or the purchaser's in- 
spection was forthwith removed from the line of flow and 
sent to a hospital. Needless to say, the latter was pretty 
large at times ; but this practice permitted an unbroken flow 
of work from operation to operation. The value of this 
practice was enhanced by the excellent handling devices 
and conveyors, which were provided everywhere throughout 
the shops. 

No Rejections After Delivery 

The plant for this work was laid out for an output of 
9,000 per day of 20 hours, but the actual output reached 
was 24,000. The quality of the first series submitted to the 
purchaser was highly commended, even after firing some of 



QUALITY CONTROL IN PRACTICE 191 

the cases three times. Not one series nor one single case 
out of the 2,500,000 was rejected after delivery; and the 
same statement holds for the complete and loaded shells. 

Mr. Lassiter, in speaking of this part of the work, recently 
said, "We were novices, so the first thing we had to do was 
to find out what we had to make, then we had to make all 
our processes alike, and finally we had to inspect everything." 

To what extent the first thing was done, is shown very 
clearly by the little 7^ by 3% inch booklets which were 
supplied to the shops. Each booklet contains an index and 
about 40 pages of blue prints, which give all the necessary 
information as to the product, the tools for making it, the 
shop arrangement, and so on. Sample pages are shown in 
Figure 44. In connection with the simple but complete 
way in which similar information was developed, attention 
is invited to Figures 45 and 46. They contain no unneces- 
sary information, yet everything needed is there. 

Shells 

The importance of getting processes under uniform con- 
trol is illustrated even better by some of the difficulties 
encountered in making the shrapnel and H. E. shells. In 
general terms, the usual processing in the early stages is to 
forge, rough turn, harden, and grind to finish. It was de- 
sired to substitute finish turning for grinding, in order to 
get greater production. The problem was to get them soft 
enough to turn, but hard enough to meet the ballistic re- 
quirements without the walls of the shell upsetting in firing. 
This, of course, involves very uniform heat treatment. 

A furnace was built 24 feet long, with six pyrometers 
spaced along the sides. The shells were placed in special 
triple pocket cradles, and were pushed into one end of the 
furnace by a pneumatic pusher. The pyrometer at the 
entrance fluctuated, but the sixth pyrometer was steady, 



SHELL Q.F. 18 POUNDER SHRAPNEL 
MARK IX/L/. 



H3.66 




Total Pressure =150 tons 
Pressure per sq. in. =33,500 lbs. 
Gauge Pressure »=-1500 lbs. max. 
(Area of band after compression) 




DRIVING BAND 
R.L. 13413 A. 



Figure 44. (a) Typical Page from Shop Instruction Book 
American Locomotive Company practice. 



192 



SOCKET 

_H 2.515!!_L 2.505^_ 




TIN CUP 
-H 2.246"L 2.228— 



No. 20 S.W.G. 
036"thick 




H2.53 L2.51- 

H 2.53" L 2.56'- 

CENTRAL TUBE 
fe25->l<r.-25->| k-.08"Class "C" Metal or Mild Steel 



M 






-About 7 8— 



Chamfer 



jr^wv/ 






_¥_ 



18 Thds. per Inch R.H. 



Figure 44. (b) Typical Page from Shop Instruction Book 
13 193 



MATERIAL STEEL CARBON 70% OR OVER 
FINISH ALL OVER 



PUNCH FOR 
DRAWING OPERATION 




*-* 



_Y ± 



"A* 



■3VL- 







3.038 > 



3.033 > 



2.788-! > 



-2.240y 
-2.465^- 



PUNCH FOR 
PIERCING OPERATION 




r- 




Y Y 



Figure 44. (c) Typical Page from Shop Instruction Book 
194 

























Toledo *18 
Style *U4 




Bliss *14 
Style*2-W 


MAP OF PRESSES IN 




Tapering-45" 2nd Tapering-18* 


CARTRIDGE SHOP 




Toledo#17 
Style *W 




Bliss #10 
Style#2-W 




Bliss%2 
Style#27 




3r 


d Tapering-18* 1st Tapertn 


s- 


L8* Heading Press-18# 






Bliss 
Trim- 
mer 












Flash 
Anneal 
Furnace 




Bliss *9 
Style#27 






Toledo #15 
Style #666 




Toledo #16 
Style *666 








He 


iding Press-18* Heading Press-4.5Heading Pres 


s-45" 




Flash 
Anneal 














Bliss #8 
Style #60H 




Toledo #14 
Style*666 




Toledo #13 
Style #856 






Toledo 
Trim- 
mer 




] 


Hack Press 




2nd indent-4.5" 


Rack Press 








Bliss 
Trim- 
mer 






Toledo 
Trim- 
mer 


















Bliss *7 
Style #60!^ 






Toledo*ll 
Style #857 




Toledo #12 
Style #856 


















■d i r> 




1 T1 










Bliss #6 
Style*60% 






Rack Press ±tack rress 




Bliss 
Trim- 
mer 




1 


lack Press 


















Bliss #5 
Style#78i-s 






Toledo #9 
Style*857 




Toledo #10 

Style*856 




C 


rank Pres 


B 


Rack Press 




Hack Press 




Bliss #4 
Style*87 




Toledo #7 

Style*857 




Toledo#8 
Style #59 X 








C 


rank Pres 


3 


Rack Pres 


5 C 


'rank Pres 


s 




Trim- 
mer 




Bliss *3 
Style #78 1 /o 




Toledo # 6 

Style #857 




Toledo #6 
Style*57 








c 


rank Press 




Rack Press 


( 


}rank Pres 


s 




Bliss *2 

Style*77Vo 




Toledo *3 

Style *58 




Toledo #4 
Style #59KS 




c 


rank Pres 


3 ( 


>ank Pres 


3 C 


/rank Pres 


3 




Bliss*l 
Style # 77^ 




Toledo*l 
Style*59 




Toledo*2 
Style*59 










c 


rank Pres 


5 


< 


>ank Pres 


3 C 


rank Pres. 


) 



Figure 44. (d) Typical Page from Shop Instruction Book 

195 



No. 6. 7-0 Clearance 
200 Ton 
L6"Centers 
5 Posts 



No. 7. 7-0 Clearance 

350 Ton ( 

6Vl'& 6'Centers 

6W'Posts 



o o 


* 1. 














o o 


*I «s 



CO y 


O 














'et 


o 


o 



No. 5. 7-0 Clearance 
200 Ton 

6%"& 6'Centers 
6 Posts 



ST o o 



No. 8. 7-0 Clearance 
350 Ton 

6V2& 6' Centers 
6V2 Posts 









4, to 




•* 




t i 









O 


.. *£, 



No. 9. 7-0 Clearance 

350 Ton, 

6Ms'& 6 Centers, 

6&"Posts 



T3 



±E 



No. 4. 6-3 Clearance 
35,0 Ton 
^6,pen-ters 
7 Posts 



<^-j)200' 

^^ 6V 3 ", 

CS^D 5P( 



No. 3. 7-6'Clearance 
Ton 

'& 6"Centers 
Posts 



No. 10. 7-0 Clearance 
200 Ton 
^"Centers 
6'Posts 



No. 2. 7-8 Clearance 

2S5 Ton 

7'siots, 4?/2"Center.s 

5V2"Posts 



No. 11. 6-3 Clearance 
350 Ton 
6' Centers ■ 
7"Posts 






Sj 


— + 




f + 




+ 








s* r 



No. 1. 5-0 Clearance 

350 Ton 

6W& ^Centers 

6^'Posts 



Figure 44. (e) Typical Page from Shop Instruction Book 
196 



QUALITY CONTROL IN PRACTICE 197 

showing that the furnace was long enough to permit equilib- 
rium to be reached. Presently it became possible to adjust 
the temperature to suit the various "heats" of steel. 

The furnace unloaded automatically through a low door 
and into a cooling oil tank, which was equipped with an 
elevator. As it soon developed that this cooling tank did 
not provide constant conditions, a 10-ton refrigerating 
plant was installed ; also two circulating pumps to keep the 
oil bath uniformly mixed. A similar furnace equipment 
was used to draw out the hard spots, which were found to 
occur from time to time if only the heat treating furnace was 
used. After heat treatment and annealing, all shells were 
scleroscoped. 

As a result of this process it was possible to substitute 
finish turning with a very fine feed, instead of grinding, with 
a resultant saving of 50 per cent in cost, no loss ballistically, 
and no loss from failure to clean up in turning. The loss 
from the latter cause, by the method previously used, had 
run as high as 20 per cent at times. 

Bullets 

The first difficulty encountered was to get the required 
amount of antimony into the lead, and in a uniform mixture. 
This was met by adding the antimony in progressive steps, 
one-fourth being put into the lead at each melting. The 
metal was then extruded into 3^-inch wire and wound on 
reels. Each bullet press used 16 reels, and operated at 90 
strokes per minute. 

The little fins left by the press were tumbled off in slat 
rumblers. Naturally some bullets got too much tumbling 
and ran out of round. As the elimination of the latter by 
means of the usual bean-sorting belt was deemed to be too 
slow and costly, a simple, inclined, gravity, separation table 
was provided. The bullets were allowed to roll down this 



198 



THE CONTROL OF QUALITY 



^ 


Is 1 ' 








„, 




% 


1* — :. os ' — i 










5 5 






<s 


;i 












« 






® 


i] 


® 










3 j 






© 


)i 


® 


S 5 $ 














© 


O I 1 




5 








1 * 


1 








© 


D^lll 


c© 


1 






i , 


t J 




® 


1 


® 


1 




a'* 


1 !! 


? S ' 




® 


1 


] ©• 


? 1 5 


s 
1 


w » 


a ; 5 


J * 3 




© 


^'L 


^© 






I 


8: ^ ^ 


1 5 % 




© 
© 


d A 


0© 
=i© 




5 


,_ i 


S 5 


' N Ji 


L « 




* Km Mn« 


SJ £dO*)9 4«0 


$S;s 






© 




3 © 


1 1 Sk^ >insv. 




S kiu. 


^ 


is i 




© 


! 


u © 


S - 1 

^? « . ,| 

5 3 "> » 
* l % I 

"k 1 ! i "' 


1 

£ = It 


! 1 


K 


K. 3 






©rC 
©--^ 




®o 


© 


J: 


5 o ? 


11 « s* 


Si *a 


•3 






* . , 




























<0 

5 


®!£ 




2«« 5 . . 

? i M . . 


Si 








\ 


5 


©o 




§ * S s ; 


* ' ' 








* 


o 




> 


1 


, ! * i ■ ' 


S3 
15 










* 


IS 












*> $ 






i- 




1 1 - * " •< » 






c « N (y 


cm <4 m 




























R|B 














■? 


© 


Sljj 


2l [ \ 


1 
* i 


* 
J 


u «: 

5 ¥ 


5 >; 

3 K. 

I 3 « 


i 




so 


© 


iu 


HO 


1 * . * 
§ 1 I s § 

■" C 5 * i. S 3 

1 5 » 5 2 3 


t j « i 

* « = * 

? s > t fe »- 

3 3 1 J * * 


i Is 

* S 3 


E * ^ 5 

< 3* I 

5 S S •- 
"53 


* 5 


| 5 

1 ! 


p ! 


® 


n 






Hi 

hi 

t >. > 

? 8: * 
s_s_s 


' * S %r 

V * s * 

S ». *! S 

? 5 Si > 

5 i 


£ * 
5 * u 
I 5 § 
k. E * 

5 j * 

1 3 a 


I; 

!i 


2 1* * 
S s 

5 E 

? £ 




"(4 


* 


t, l « « i « 

? 3 3 a 5 
s ¥ a 1 s s 






H-Z-r 




| 2 <* l 0>S f- a 


en J J « J $■ 


3 J i- 




c» «l + 







j o, 







O 






2 


> 


<i) 




a 





O 


-a 





a 


J 


a 


a 




rt 


3 











a 
< 






ta 



QUALITY CONTROL IN PRACTICE 



199 











J 


| 


























■ 


























































































































S i 
































1 ^s 






5 , | 


- > 


























































-> * 1 fjl 






„ 
































k i il) 






5 r 






































-5 ^ 






































* ^ 
































s 






1 i 








































$ $ 


» 




































« 


































^ 5 > 


5 


































! ? * ; 






































u 






























y 




s ~ & 


4 

i 






























^ 
g 


>: 




2 * - 


* 






































5 






























5 


> 




1 ? « j 


5 






























S 






k * „ 
































\y 






































§ 






3^ 


































|^ Op — >■ 


Q 


$0 § 


§ 
4 






























© 














t v i 








































* L * 








































8 fc « 
































© 






© V 


"5 % 




































• U\ if 


r- a 


-. «) 


n 


01 


- * 


, 5 


01 


(^ 


■n 


^ 


^ 


(0 


^ 


"i 












00 00 qi 


01 ^ 


5 t 


^ 


S * 


"? 


s 




s 


■n 


f< 


s 


5 


5 












5 5 S "<• 
-, 1 k * J 


k k k 


k 4. 


■- k 


k 


. k 


k 


k 


■i. 


k. 


k. 


k 


k 


k 


k 




© 






^ 


5*1. * 


> k ^ 


^ ^ 


- ^ 


> 


- ; - 


> 


i. 


< 


i 




k 


< 








































I 






































8 


© 






© 


O £ 5 








4 

•3 
























© 






©s 


*2 *? 

1 ,5 




y. 






i 

! 








t 


J 


1 


■a 








© 






© 


•T 5 n 

S 2 * 5 * 
5 «• 51 n * 

u $** S 

I § § - * 

S 5 S 5 x 

*• ^ 2 5 >3 

S K $ 


C k 

•> 5 ^ 
■ § " 
$ i ^ 

cj <C * 


* 
is 5 


5; 
> * 

i ? 

s 1 

* * 

; 8 


8! 




; 
? 


2 
> 

S 

N 

0, 




13 

K 


<o 


J 

a 




* 
; 

Q 


k 

5 


1 

5; 






«| 


s ° 




S ^ 5 4 


<» 






























5 S 




5; 3! * «*. 


< 










^ 






4 








* 










^°; 












|> 






? 






























'I. 














? 






k. 




k ^ " * » 


j j 3 
; j ? 


{ * 


i - 


Q 


5 


5! 


* 


* 


5 


* 

1. 


* 


t 


^ 


j 








tj <S ? 1 ^ 


t 38 


5 ? 


Q 


5 


s 


1 


i 


* 

•o 


§ 


q 


k 


5 


S 


? 








!j => « 
































* 
% 




5 < K O £ 
































£ 




^ 




































"5 
































| 




« 

































3 

j a 

.2 u 
a; .S 

s I 
s 
£ < 



3 k? 



200 THE CONTROL OF QUALITY 

table and thus classify themselves automatically, as regards 
their lack of sphericity. 

By such methods as those just related a supply of bul- 
lets of the required hardness and roundness was soon ob- 
tained. The plant requirements were 60 tons per day, but 
they were , soon able to supply other plants which had 
encountered trouble in making bullets. 

Time Fuses 

Everyone knows of the grief encountered in making and 
loading time fuses, so that a mere statement that the Ameri- 
can Locomotive Company produced millions of them suc- 
cessfully, with no explosions or injuries to employees, should 
be indicative of the care that was taken. They had to find 
out that no two lots of powder are sufficiently alike to per- 
mit loading for a uniform burning time of 21 seconds+or — 
0.2 second. They started without any knowledge of the 
business and had to feel their way. But they did know the 
principles which must be followed in making anything. 

They developed a simple type of powder blender and 
created a larger supply of uniform powder. Then they 
learned that powder will not pack to burn accurately unless 
the humidity of the air is constant, so the air for the loading 
rooms was first dried by freezing, and then conditioned to a 
standard humidity. In order to make sure of the ±0.2- 
second limits in burning time, they paralleled the com- 
mercial type of chronographic instrument with a time- 
measuring instrument of their own design. 

The following item is significant : The second lot of fuses 
went wrong in burning time, and the trouble was located 
promptly as occurring in one of the 1 7 separate loading sta- 
tions. There were seven men in that room instead of the 
usual five. In the hot weather this caused sufficient varia- 
tions in humidity to affect the firing time. Would it have 



QUALITY CONTROL IN PRACTICE 201 

been possible to locate such a difficulty promptly without 
an efficiently handled inspection service? 

Quality First — Then Quantity Follows 

Mr. Lassiter believes in inspection, just as he knows that 
the first move toward quantity production is to make things 
right. In this work the ratio of inspectors was I to every 4 
workmen. 

The percentage of work rejected in process inspection 
varied widely from time to time, as must always be the case. 
When the estimates were made for submitting proposals for 
the contracts, a 5 per cent loss in manufacture was allowed 
for. When starting on production, the inspectors were very 
rigid and the temporary rejections amounted to about 19 per 
cent. These rejections were held in suspense, however, 
until a hospital could be organized for reclaiming some of 
the product. This was done, as already stated, so that 
rejections could not stop the progress of the flow of work 
through the machines. As the work progressed and the 
organization learned more about the business, rejections 
began gradually to decrease, so that upon the completion 
of the job it was found that the total losses from every 
cause in the process of manufacturing was only 6 per cent. 
The total loss therefore exceeded the estimated loss by 1 per 
cent, but the reduction in cost below the estimated cost 
greatly exceeded the 1 per cent excess of loss. 

Mr. Lassiter states: 

If we had not provided our enormous staff of inspectors, who 
checked each operation on the work as it progressed through the 
shops, with limit gages with very close tolerances our loss would 
have run into an enormous sum of money. Therefore, one of the 
causes of our great success in the economical manufacture of 
shells was our large staff of inspectors, the tolerances which we 
established on the limit gages and the system which we installed. 



202 



THE CONTROL OF QUALITY 




QUALITY CONTROL IN PRACTICE 203 

It is to be regretted that the very many other interesting 
features of this work cannot be presented here. The meth- 
ods pursued, as shown by the salient features already men- 
tioned, strikingly illustrate the premises laid down at the 
beginning of the chapter. 

Liberty Motors at the Lincoln Motor Company 1 

The name of Leland has long been associated with the 
idea of precision and fine workmanship carried to the nth. 
degree. Henry M. Leland began his career in the Spring- 
field Arsenal, and later extended his experience from firearms 
into the field of manufacturing sewing machines and ma- 
chine tools. With his son, Wilfred C. Leland, he was one of 
the pioneers of the motor car industry. Together they 
carried the Cadillac factory to a point where hundreds of 
machine operations were held within 0.0005 i ncn of the 
absolute dimensions. 

In 191 7, they established the Lincoln Motor Company 
to build Liberty engines for the United States Air Service. 
The first contract, dated August 31, 1917, was for 6,000 
engines, and contemplated an ultimate output of 70 
12-cylinder engines a day. Henry M. Leland, then 74 
years old, made this pledge to General Squier: 

It's true that we have no factory now. But we have the know- 
how. We will guarantee to build within a specified time as many 
motors and of at least as good quality as will be produced in any 
existing plant. 

The land was acquired and an $8,000,000 plant built and 
equipped. This called for over 90,000 special tools, among 
which were 6,522 separate designs. Mr. Leland told the 
writer that the large number of tools and gages as well as the 
time required to get started was questioned by some of the 

1 The statements made are taken from "A Pledge Made Good by Deeds," published in 
the Detroit Free Press, and are supplemented by data obtained by the author in conversation with 
Henry M. Leland during a visit to the Lincoln Motor Company's factory. 



204 



THE CONTROL OF QUALITY 









9-1 


7-20 4 Sheets, 
Sheet No. 1 




LINCOLN MOTOR COMPANY 








Operation Sheet 








Part Name: 


Housing for Trans. Control Lever 




Pa*rt No. 2002 










Kind of 
















Machine, 
















Machine Size, 








Oper. 


Name of 


Dept. 


No. 


& Special Tools 


Tool 


No. 


Commercial 


No. 


Operation 


No. 


Req'd 


Per Set Up 

L. M. Co. 

Mach. No. 


No. 


Req'd 


Tools Per Set Up 


5 


Inspect 


M-io 


1 


Bench 

Gauge for check- 
ing depth of 
core from un- 
finished face 
of boss 51/2 
dia. 


1 1948 






10 


Snag 


K-i6 












12 


Inspect 


M-36 




Bench 








13 


Sand blast 


K-17 












IS 


Rough and fin- 


K-23 




#6 W & S Screw 










ish bore, 






Machine 


1965 


1 


10" Face plate 




rough tap 




1 


Face plate fix- 






(Std. W & S) 




large hole 






ture and lay- 






#i96-A 




and rough 






out 


4128 


1 


1 3/4-16 Go thd. 




and finish 




1 


Tool block for 






gage Go & No 




face base 






rough and fin- 
ish facing 






Go 










base 


4135 


1 

1 


1.686 Go plug 

gage with 

handle 
1.690 No Go plug 










Bar for roughing 
and finishing 
inside dia. and 




1 


gage handle 
1.654 Go plug 
gage with 










thread dia. 


4136 


1 


1.656 No Go plug 
gage handle 








1 


Gauge for set- 




3 


#641 Warner & 










ting cutters 






Swasey flanged 










on finish bor- 






tool holder 










ing bar 


4138 


1 


Shell reamer 








1 


Alignment bar 






1.655 dia. 










for 1 1/4-1- 




1 


Holder for shell 










3/8-1. 654and 






reamer #8 Std. 










1.686 holes 






Tool Co. 










with stop col- 
















lar for testing 




1 


Floating tool 










squareness of 






holder W & S 


1 








base 


4506 

! 


1 


#M-652 



Figure 48. Typical Operation Sheet — Lincoln Motor Company 



QUALITY CONTROL IN PRACTICE 205 

M-16 Part 2002 

HOUSING FOR TRANSMISSION CONTROL LEVER 

1 . Observe for burrs, cracks, sandholes and other casting defects, also 
that radii, chamfers and countersinks are as per Blue Print, 

2. Observe four 13/32 drilled holes and 3/4 dia. counterbore. 

3. Check 8" over all height with Template Tool #4512. 

4. Check 10-24 threaded hole with Go and No Go Plug Thread Guages. 
The "Go" end of guage must enter to the depth as shown on 
drawing. Threads may be passed as O.K. if they are a snug fit on 
"No Go" end of gauge. 

5. Check 1-3/4-16 threaded hole with Plug Thread Gauges. The Go 
end of gauge must enter to a depth of 1/2" as shown on drawing. 
Threads may be passed as O.K. if they are a snug fit on No Go 

gauge. 

6. Check .999-1.001 reamed hole with Plug Gauge. 

7. Check 1. 654-1. 656 diameter bore with Plug Gauges. 

8. Check .1 8657.875 diameter reamed hole with Plug Gauge. 

9. Check .248/. 250 hole with Plug Gauge Tool #4514. 

10. Check .748/. 750 diameter reamed hole with "Go" and alignment 
Plug Tool #4915, also with "No Go" Plug Gauge. 

n. Check alignment of .248/.250 and .999-1.001 holes with Tool #4508. 

12. Check 1-5/64 counterbore depth and diameter with Template Tool 
#45ii- 

13. Check depth of 3/8 diameter of counterbore with Tool #4920. 

14. Check 3/8" thickness of bosses with Tool Snap Gauge .365-385. 

15. Check 7/8" dimension faces of bosses with Snap Gauge Tool #4509. 

16. Check angle and radius on top with Tool #4707. 

17. Check .307-317 dimension with Tool #4919. 

18. Check 1-5/8 dimension with Tool #4921. 

19. Check 1.810/1.820 dimension with Bar Gauge, Tool #4513. 

20. Check 1. 624/1. 630 dimension face of bosses with Bar Gauge Tool 
#5440. 

21. Check 7-1/2 dimension, 6-9/16 dimension and 5-7/8 dimension for 
location in relation to 1-1/4 bore with Tools #10540-10541 & 10542. 

22. Check 7-1 1 /16 dimension depth of bore to base with Tool #4510. 

23. Check alignment of 1.654/ 1.656 Dore with threaded hole and square- 
ness with base, the 1.990/2.0 10 dimension, the .905 /.g 10 dimension 
and 1. 148/ 1. 1 54 dimension, with fixture Tool #4507. 

24. Check the 13/32 depth of .248-250 hole with Tool #10775. 



Figure 49. Typical Instructions for Inspection — Lincoln Motor Company 



206 THE CONTROL OF QUALITY 

government inspectors, but that he considered it absolutely 
necessary to get things right before beginning production. 

The company built up an organization of 6,000 people 
and produced 2,000 Liberty motors within one year of its 
formation. Before the close of 191 8, it produced the largest 
number of motors in a single day, the largest number in a 
single month, and the largest total rolled up by any manu- 
facturer. It completed its final contract 16 days ahead of 
schedule, and received the highest commendation for its 
motors. 

It is stated that the leading English manufacturer, with 
3 years of aircraft engine experience and 10,000 employees, 
was producing at the rate of 50 motors per week. With this 
for a background, it is easier to measure the achievement of 
the Lelands, for the Lincoln Motor Company, with 6,000 
employees and after only 1 year's development, was pro- 
ducing at the rate of 50 motors per day. 

Mr. Leland has always been guided by a desire to do 
things right. Quality is his hobby and he carries it to the 
point of gathering his men together in little groups in the 
shops and talking quality to them. Furthermore, he knows 
the precision that is necessary for such work and how to get 
it, as is evident to anyone who has the privilege of going 
through the shops of the Lincoln Motor Company. The 
shops show it in their equipment and management. What 
is more important, the work in process shows it. Several 
illustrations which bear this out are to be found throughout 
this book, where they have been placed to exemplify certain 
methods. In particular, attention is invited to Figures 6, 
8, 12, 15, 48, 49, and 64. 

Remington Arms Company — Springfield-Enfield Rifle Production 

Our armies in the field never lacked American-made 

small-arms and small-arms ammunition, a statement that 



QUALITY CONTROL IN PRACTICE 207 

hardly holds for any other of their arms equipment. More 
than to any other one man, the credit for this fact is due to 
the war time Director of Arsenals, Brigadier-General John T. 
Thompson, U. S. A. (Retired), D. S. M. He developed the 
war plans of the Army Ordnance Department as a result of 
personal experience in the Spanish-American War, and had 
charge of developing the Springfield rifle, thus gaining 
recognition internationally as a small-arms expert. More 
recently, in association with his son, Colonel M. H. Thomp- 
son, he has brought out that remarkable arm known as the 
Thompson sub-machine gun. 

I In September of 1914, he told the writer one afternoon, 
on the front steps of the State, War and Navy Department 
building in Washington : 

We are going to be forced into this war sooner or later. I am 
going into civil life (he had just retired as a colonel) to help teach our 
people how to make military rifles and rifle-making machinery. 
There are not nearly enough military rifles in the world. This 
country will be flooded with foreign orders, and these orders can 
be used to get the private armories ready to meet our own needs 
later on. All our military rifles have been made heretofore at 
Springfield or Rock Island in government plants only: and making 
sporting rifles is not the same thing as making millions of military 
small-arms exactly alike. 

So General Thompson joined the staff of the Remington 
Arms Company, where he laid the plans for the huge armories 
at Bridgeport and Eddystone. Subsequently he went to 
the Eddystone plant (the Remington Arms Company of 
Delaware) and acted as consulting engineer during the 
manufacture of Enfield rifles for the British government. 
When the United States entered the war he was recalled to 
Washington to take charge of the production of small-arms 
and their ammunition. 

Some time later came the so-called "broomstick" in- 
vestigation by Congress, following the tardy discovery 



208 THE CONTROL OF QUALITY 

that this country did not have rifles enough to arm our 
troops. Of course we did not. Congress had never given 
us a chance to have them. To those most interested tech- 
nically, the outstanding feature of the investigation was the 
discussion of tolerances. Many of the private manufac- 
turers wanted tolerances and limits increased — "to get 
greater production." General Thompson insisted that the 
contrary was true, and that even closer limits would result 
in greater production as well as in better arms. Not only 
that, but he had the courage to insist on converting the 
Enfield rifle to use the better Springfield cartridge ; hence the 
Springfield-Enfield. This meant that 14 parts had to be 
changed, and the necessary delay in changing tools and 
gages had to be accepted. As a further step toward greater 
precision, also at the expense of time at the start, the gages 
of the different armories and arms factories were brought 
into accurate agreement. Was the General correct in his 
contention that quality preceded quantity production? 
Let the facts speak for themselves. 

In the first place, rifles were ready for all troops at least 
by the time they sailed for Europe ; and they never lacked 
them in the field. Several plants were engaged in making 
these arms, but the greatest output was delivered by the 
Eddystone armory, where the daily output reached the re- 
markable total of 5,000. More interesting still, the number 
of rifles finally assembled per man per day started at 40 
(which according to the best data available, was formerly 
considered a good figure for this rifle), then increased to 120, 
and finally reached a figure of 160. As to the quality of the 
American rifles thus produced, for this was undoubtedly a 
factor in the fine shooting of our troops in the field, let the 
Germans before Chateau-Thierry (and elsewhere) tell the 
story. According to report, they repeatedly mistook rifle 
fire for machine guns and shrapnel. 



QUALITY CONTROL IN PRACTICE 209 

Quality Is the Road to Production 

To summarize: Mr. Lassiter developed an organization 
of 40,000 men and produced 25,000 tons of munitions per 
day with only 6 per cent of spoilage; Mr. Leland started 
with not even the land for a factory, built a plant, gathered 
6,000 workers and produced 2,000 Liberty motors to meet 
rigid requirements — all in one year; General Thompson 
directed the planning which resulted in our enormous war 
time rifle production. At the basis of each of these diffi- 
cult manufacturing achievements is the guiding principle of 
quality control. 



CHAPTER XIII 
MEASUREMENT AND ERRORS 

The Evolution of Measuring 

Measurement is the foundation upon which the exact 
sciences rest. Since the manufacturing arts are — or should 
be — but the application of the laws of science in practical 
form to meet our daily needs, it follows also that measure- 
ment is the proper starting point in the arts just as it is in 
the work of pure science. In fact, it has long been recog- 
nized that the degree of accuracy with which measurements 
are made is the best criterion of progress in the arts. The 
process of measuring permits comparisons to be made and 
recorded in form for use. By it we may note the differences 
and likenesses of similar things, also the degree of such like- 
ness or dissimilarity ; and it is by such comparison that prog- 
ress can be recognized. Some changes show retrogression 
and others indicate improvement, but without the ability 
to measure them it would be quite impossible to advance 
either science or art in a way sufficiently systematic for 
practical usefulness. 

When the attempt is made to manufacture a number of 
like things, some sort of measuring process is absolutely in- 
dispensable. Hence the importance of understanding what 
the process involves. 

The history of the development of the standards of 
measuring (used here in its widest sense to include weighing 
or similar operations) presents a specially interesting and 
fascinating picture of man's material progress. 1 It does 

1 See further "The Progress of Science as Exemplified in the Art of Weighing and Measuring, ' ' 
by Professor William Harkness, U. S. Naval Observatory — presidential address before the Philo- 
sophical Society of Washington, 1887. (Smithsonian Report, 1888.) 



MEASUREMENT AND ERRORS 211 

not serve the present purpose, however, to digress in that 
direction, other than to note the rise of accuracy that has 
accompanied the evolution of our present standards. It is 
relatively only a short time ago that the most precise and 
scientific laboratory methods were quite incapable of real- 
izing the accuracy that is commonly attained in modern 
shop practice, with much less effort and care. Furthermore 
we are able to measure many things today that our forebears 
never thought of measuring — and the end is not yet. 

There are some features of the evolution of measuring, 
nevertheless, which must be considered in connection with 
what follows. They are illustrative of the procedure which 
must be observed in order to develop in a logical way the 
processes of measuring necessary for controlling quality 
in manufacturing. 

The Selection of Characteristic Qualities for Measurement 

Suppose we assume that we have to make a quantity of 
articles — bricks perhaps. They are to be as nearly alike as 
may be consistent with the commercial restriction of econ- 
omy. Let it be assumed also that we have no means or 
scheme of measurement. The first step necessarily must be 
in the direction of selecting the characteristics in which the 
articles are to agree. These characteristics, which deter- 
mine the quality of the article, are, of course, sensed and 
evaluated by us through the physical means with which we 
perceive them. Thus if we were concerned with bricks, the 
essentials would be shape or form, size, strength, weight, 
surface finish, color, and so on. For practical purposes, we 
could get along very nicely without paying any attention to 
any of these points except shape, size, and strength, but as 
the art of brick-making progresses, the demand increases 
for greater uniformity in the less utilitarian and more 
aesthetic characteristics. 



212 THE CONTROL OF QUALITY 

The economist says that manufacturing, as a process, 
inhibits making beautiful things. 

Individuality is the essence of art; to be beautiful it would 
seem that a thing must bear the impress of its maker's personality. 
There is little room then for specialization in the making of beautiful 
things. If we want the material apparatus of life to be beautiful, 
we must be content with less of it ; we must choose between a great 
many ugly and ordinary things and a few beautiful and unique 
things. 2 

This statement is true only if we are content to permit it 
to be true. It should be a pleasant duty for the manufac- 
turer to dispel this somewhat common, although fallacious 
belief, and the way to do it is by the first step just indicated. 
Keen and searching analysis of a product will show its char- 
acteristic qualities, some of which contribute to its useful- 
ness while others make it pleasing to the senses. Economy 
of manufacture reaches its greatest efficiency when every 
characteristic is controlled to uniformity with deadly 
accuracy, but its product need not be ugly or lifeless, 
unless we choose to ignore all but the most utilitarian quali- 
ties. If the model is beautiful, its beauty can be repeated 
indefinitely with proper care and attention to the pertinent 
details — a business in which little things become paramount. 
Is not the modern automotive engine an article of beauty? 
It is made so by precision manufacturing, which also makes 
it an article of commerce. If it could be made, and were 
made by the "individualistic" methods of the artist, no 
ordinary man could afford to own one ; nor would the auto- 
motive art have made such rapid strides. 

Standard Samples 

Having selected the characteristic qualities which we 
wish to have alike in all the articles we are to manufacture, 






2 Henry Clay, Economics for the General Reader. 



MEASUREMENT AND ERRORS 213 

the next step involves the selection of a standard of com- 
parison, and this standard must always be some tangible 
physical thing. To return to the case of the brick, we prob- 
ably should select a brick and say, "This is of the shape and 
size wanted. We will call this our standard sample for 
shape and size." Then perhaps we might select another as 
the standard sample to show the desired color. 

As a matter of fact, the method of comparison by using 
standard samples is the accepted practice in more than one 
industry. In many cases it has to be. Take the matter of 
making cigars. The tobacco must be graded in several 
ways, as well as by odor (and possibly taste), to secure the 
desired bouquet. There is no instrument as yet, to measure 
such qualities — nor is there even a classification of them. 
Any uniformity that is secured must be by comparison with 
some sample or samples arbitrarily selected as standard as 
regards both raw material and finished product. Even if 
samples are not at hand, they exist in the memory of the 
expert whose judgment is relied upon for the grading' — and 
the statement still holds in principle. 

Color is measurable, but the methods and apparatus find 
little application as yet outside of the physics laboratory. 
The principal industries in which color is a dominating 
quality, such as the textile industries and those of similar 
type, have made the first important step toward standard- 
izing by the adoption of the so-called "standard color card " 
(see Chapter XXI), which shows the colors adopted as 
standards in the form of classified standard samples. 

The selection of a standard sample can hardly be called 
measurement. It is rather the first crude step toward 
measuring, as we understand the term "measuring" when 
speaking of weight or dimension. But it is a very necessary 
link in the chain of development. Perhaps it may be asked, 
Why carry the process further if such samples will serve the 



214 THE CONTROL OF QUALITY 

purpose? The answer is best found by considering what 
must be assumed when comparison is by standard samples. 

Dangers of Standard Samples 

The first assumption is that several samples are suffi- 
ciently alike for practical purposes. If a number of samples 
are available to choose from, this may reasonably be 
assumed to be true, but only up to a certain degree of likeness. 
Further progress toward general uniformity is blocked 
when that stage is reached. 

The most dangerous assumption which must be made, 
however, is that the standard sample will not change with 
time. It is bound to change. That is one of the few great 
laws of nature we are sure of. Everything changes all the 
time, and very few samples indeed could be found that 
would not alter perceptibly — if we had anything to use as a 
measure for detecting the change. What is more to the 
point, the oftener we use our standard sample in practice, 
the sooner does it alter in the very characteristic for which 
it was chosen as a standard of comparison. Our old friend, 
the brick, would soon wear, and abrade away from its 
original size and shape, if we used it to compare with new 
lots of bricks. Also, the one we selected as a sample of the 
desired color would be quite sure to fade with exposure to 
light, or to grow darker from handling. At best, any sys- 
tem of uniform manufacturing which is based on standard 
samples alone requires that the most unusual precautions 
be taken to safeguard the standards. The use of master 
gages and the care required in gage-checking may be in- 
stanced in illustration. 

Measurement by Comparison with a Standard Scale 

The next move toward a more efficient means of making 
comparisons in order to secure uniformity of product, is in 



MEASUREMENT AND ERRORS 215 

the direction of greater general usefulness, simplicity, and 
permanence of results. Convenience, if nothing else, re- 
quires that we obtain a standard of more general applicability. 
Suppose we take dimension as the quality to illustrate this. 
Once we assume an arbitrary standard of length with a 
suitable scale of divisions, we can dispense with the business 
of comparing brick with brick, so far as dimension is con- 
cerned. In fact, with such a means of measurement, we are 
in shape to compare dimensions by themselves, without 
regard to the particular articles whose size is involved. 
Thus the idea of true measurement appears, because we are 
able to reduce our comparisons to the abstract form of 
figures. Any dimension is then expressed in the form : 

the given length 



The measured length = 



the standard of length 



The point to be borne in mind is that when it becomes 
desirable to carry the control of quality beyond the standard 
sample stage, the first step is to develop a graded scale which 
will permit us to express the measure of the quality in figures. 
The latter makes us reasonably independent of the dangers 
of standard samples. Needless to say, such a scale itself is 
always, in the last analysis, based on some tangible and 
arbitrarily selected object which is taken as the common 
standard. But the general usefulness and wide applica- 
tion of the selected object warrant the precautions neces- 
sary to insure permanence. Thus dimension and weight, 
the evolution of which has been carried to the practical 
limit, may be taken as amply safeguarded. The standards 
in this country are represented by certain weights, bars, etc., 
which are kept in the vaults of the Bureau of Standards in 
Washington. (See Figure 50.) That is to say, all our meas- 
ures refer back to certain objects which are arbitrarily 
selected as the standards. The standard of length is now 



216 



THE CONTROL OF QUALITY 



reproducible for any reasonable requirement of accuracy, 
because its measure is known in terms of light waves. 




Figure 50. The Standards of Weight and Length for the United 

States 
Kept in the vaults of the Bureau of Standards at Washington, D. C. 



Nevertheless it is still true that we cannot get away from an 
arbitrarily chosen standard even then, because we must use 
a given light wave, such as sodium, and the light must be 



MEASUREMENT AND ERRORS 217 

made or taken from sources selected as standard, and 
measured with a certain definitely selected and calibrated 
equipment. 

The choice of the fundamental units for measurement 
should be made with care. They should be convenient, 
should permit accurate comparisons with other quantities 
of the same kind (see Professor Harkness as referred to 
above), and should permit of accurate comparisons regard- 
less of time and place. Scientists ordinarily use as funda- 
mental units for physical measurements a definite length, a 
definite mass, and a definite unit of time. Most of our 
ordinary measurements are based on these units or some 
combination of them, e.g., electrical measurements, etc. 
Characteristic qualities which are not measured outside of 
the laboratory as yet, usually will be found to be measurable 
in terms of three constants. The fact that sound is meas- 
urable in terms of tone or pitch, amplitude, and timbre indi- 
cates a line of attack when the problem arises of measuring 
noise due to vibration. The color constants are hue, purity 
or saturation, and luminosity or brightness (see Chapter 
XXI). 

The Measuring Instrument 

The final step in the evolution of measurement is the 
development of instrumental means for making comparisons. 
Their need springs from the desire for greater accuracy, 
which requires the use of something that is less subject to 
personal error and differences from individual to individual. 
This impersonal quality of the instrument flows from the 
fact that it is more positive in action than any unaided 
comparison by means of our senses can possibly be — a result 
that is accomplished ordinarily by enlarging or magnifying 
differences in reading, so that errors may be detected with 
greater ease. 



218 



THE CONTROL OF QUALITY 



In using a finely calibrated scale, for example, the point 
is soon reached where finer readings are impossible, and 
further progress toward greater accuracy is blocked. Sup- 
pose the scale is a high-grade flat steel scale 6 inches long, 
marked off in fiftieths and hundredths of an inch. If this is 




Figure 51. Method of Using Hub Micrometer Caliper #241- 
Sharpe Manufacturing Company 



-Brown and 



applied in the attempt to measure a block of steel, say, 
about 4 inches long, there will be considerable doubt as to 
which of two of the hundredths marks is the closest to the 
block's size. If the block is longer, the difficulty becomes 
greater; and if it is longer than the scale, an accurate read- 
ing is much harder to obtain. The use of a magnifying 
glass permits closer reading, but the use of an end measur- 
ing instrument, which makes positive contacts in place of 



MEASUREMENT AND ERRORS 219 

side-by-side comparison, renders easily possible a much 
greater precision of measurement. 

The use of instruments permits the application of means 
for enhancing errors and thus permits closer reading. As 
most of the means ordinarily employed for accomplishing 
this are illustrated in the following chapters, we may note 
meanwhile only some of the features which such instru- 
ments should possess. 

No instrument is worth using in the factory unless it is 
sure to measure more accurately than can be done without 
the instrument. At first thought this may seem a common- 
place, but it seems so only at first thought, for the reason 
that some instruments are apparently more accurate merely 
because they are sensitive. An instrument has great sen- 
sitivity when it answers (or shows a change in reading) for 
a very slight change in the thing being measured or in the 
conditions under which the measurement is made. It is 
desirable to note this difference between sensitivity and 
accuracy, because the two are sometimes confused. A 
balance whose indicating pointer answers to a very slight 
change in weight, may still be quite inaccurate. 

The converse is true also, because an accurate instru- 
ment may lack sensitivity. In the latter instance the fact 
should be known, because it sometimes happens that the 
lack of sensitivity results in a lag. It is therefore important 
to know how long it takes a sluggish instrument to show a 
correct reading. But in order to know what degree of 
accuracy an instrument is capable of showing it must be 
possible to check its precision, and this requires a more 
exact standard for checking purposes. It is for this reason 
that emphasis is laid on the necessity for control centers or 
laboratories for the control of the quality concerned. Thus 
a later chapter (XVII) deals with an ideal control center for 
dimension, as typical of any such control centers. 



220 THE CONTROL OF QUALITY 

In this discussion of instruments it will be noted that no 
attention is being paid to certain general requirements for 
measuring apparatus with which everyone is familiar, such 
as ruggedness, precision, facility for making direct meas- 
urements without corrections, general suitability to the 
requirements of the work, and so on. 

Danger of Overgraduation 

It is desired, however, to direct attention to some of the 
qualities in such instruments which are frequently over- 
looked, and thus make accurate measurements out of the 
question. One of these oversights, as a case in point, is 
what may be termed an "overgraduation" of the instru- 
ment. One of the great dangers faced by the technician, 
as by everyone else, is that of fooling one's self. It is vi- 
tally necessary in manufacturing to be sure of the facts — 
especially as to measurement. Therefore an instrument 
which is calibrated to permit closer readings than it is ca- 
pable of making is to be avoided with care, or at least used 
with a knowledge of its probable errors. 

To illustrate — the chief engineer of a large concern was 
criticized because his plans said that certain dimensions, on 
tools, should be held within .0002 inch, the specific charge 
being that such precision was uncalled for and would lead 
to unnecessary cost in the tool-making shops. He answered 
by asking "What do you think that requirement for .0002 
inch means?" Of course, he was told that everyone as- 
sumed it to mean .0002 inch, as stated. Much to their sur- 
prise he replied — " It does not. I intended it to mean what 
our tool-makers think is .0002 inch. In other words, what 
I am after is the degree of accuracy in workmanship which 
our tool-makers produce when they think they are working 
to within .0002 inch of the stated dimension. If you think 
that is the same as .0002 inch, suppose you check their 



MEASUREMENT AND ERRORS 221 

work with our Pratt and Whitney measuring machine. If 
you do, you will find that what the tool-room thinks is a 
precision of .0002 inch is actually over twice that, although 
they are perfectly sincere in their belief. They are doing 
the best they can with the instruments provided, which 
happen to be calibrated in ten-thousandths. These instru- 
ments may be capable of such accuracy, but as used in our 
shops, no such result is obtained." 

Every once in a while a factory is found whose drawings 
call for exceedingly close adherence to the absolute dimen- 
sion, although the shop is not equipped, except by the mark- 
ings on the instruments, to work to any such degree of accu- 
racy as is prescribed. Usually all hands are quite sincere in 
believing that they attain the requirements stated on the 
drawings, but they merely fool themselves. Why do so, 
however, when it is so easy to possess the truth? 

The Need of a Final Check 

Not very long ago the chief inspector of a factory whose 
work required a high order of accuracy for a very special 
sort of work was asked to produce his final standard of di- 
mension. He pointed out the usual standards supplied 
with micrometer calipers. His questioner said, "But I 
asked you to show me your final standard — your ' court of 
last appeal.' " The chief inspector blushed and said, "We 
haven't any!" Later he added in self-justification, "I've 
asked for gage blocks several times, but they never gave 
them to me." Does your chief inspector, by any chance, 
happen to be in the same fix? 

By the same token it is equally erroneous practice to 
expect accuracy when the instruments provided do not per- 
mit of close enough reading. A pressure gage with a 2 -inch 
dial, calibrated by 5-pound intervals, will hardly permit the 
process to be held to closer than 5 pounds. Yet just such a 



222 



THE CONTROL OF QUALITY 



case came to light during the recent overhauling of a process 
in which a close adherence to a given standardized pressure 
was vitally important for securing a uniform product from 
that process. It is questionable as to which is worse — a me- 
chanic who thinks he is doing accurate work because an 




Figure 52. Setting a Johansson Adjustable Limit Snap Gage by Means of 
Johansson Gage Blocks 

inaccurate instrument says so, or one who is trying to do 
accurate work without a clear reading instrument to guide 
him. Neither condition need exist, which makes their 
occurrence all the more lamentable. 



The Choice of Instruments 

In step with the preceding is the failure to realize that 
practically all instruments are less precise over a part of 



MEASUREMENT AND ERRORS 223 

their range than they are for the greater part of their range. 
Furthermore, at the part of the range where greater errors 
occur the measurements are likely to be subject to greater 
variations under different conditions of use. This is true in 
marked degree for the smaller readings of instruments which 
are inherently afflicted with an initial friction. It is true 
also for instruments whose design and construction involve 
backlash; and, naturally, the maximum errors may occur 
where the backlash may develop to the greatest degree. As 
an example of error resulting from initial friction, consider 
a balance. It may be extremely accurate for large weigh- 
ings, but will show very large errors indeed for weighings 
made at the threshold of its scale. Accordingly the smaller 
weighings should be made on a balance of smaller total ca- 
pacity as the smaller readings are thus expanded to a size 
that is perceptible. The conclusion is inevitable, that the 
instrument should be chosen with reference to its capa- 
bility to meet the requirements of a given situation. It 
must not be expected to meet all requirements. You cannot 
weigh everything with one huge pair of scales. But the 
way to determine the suitability of the instrument, or to 
select a suitable instrument for a given purpose, is to be pre- 
pared to check the work of that instrument — by some 
superior method of measurement, which is many times more 
accurate than the instrument which is being checked. 
Otherwise you cannot be sure of your facts. 

The Precision of Measurement 

In developing a method or process of measuring it was 
observed that the first step involves the use of an arbitrarily 
selected standard for comparison. Presently a point is 
reached where observations fail to agree, and this point fixes 
the limit of precision obtainable by such method. Further 
improvement is to be sought through devising a scale of 



224 THE CONTROL OF QUALITY 

more general applicability which permits not only of stating 
measurements impersonally in the form of abstract figures, 
but also securing an additional degree of accuracy in most 
cases. This method also soon reaches its limit of precision, 
and further progress toward more exact measurement must 
make use of still more impersonal methods by means of in- 
struments. While this last step usually gains much greater 
fidelity to the absolute measurement, nevertheless it too 
reaches an ultimate limit of precision beyond which meas- 
urements of the same thing under like conditions are not in 
agreement. This situation follows an earlier stage where 
measurements by different observers, working under the 
same or slightly different circumstances, do not check. 

Thus Langley, in the discussion of small irregularities of 
his bolometer records of the solar spectrum, said : 3 

When we approach the limits of vision or audition, or of per- 
ception by any other of the human senses, no matter how these may 
be fortified by instrumental aid, we finally perceive, and always 
must perceive a condition, a condition still beyond, where certitude 
becomes incertitude, although we may not be able to designate 
precisely where one ceases and the other begins. This is always 
the case, it would seem, on the boundaries of our knowledge in every 
department, and it is so here. 

Inevitably, then, a certain critical point is reached for 
any given set of conditions, where errors enter, and this is 
entirely apart from the ever-present assurance of occasional 
accidental errors. Of course we know that errors are bound 
to occur — the theme of our study has been throughout that 
quality is varying continually — consequently the readings 
of our measurements of quality will vary. 

The term "precision" is a confession that absolutely 
correct measurement is impossible of realization. Accuracy 
means exact conformity to the absolutely true standard. 

3 Joel Stebbins, "Observation vs. Experimentation," Science, January 13, 1922. 



MEASUREMENT AND ERRORS 225 

Absolute accuracy implies freedom from error, hence for 
practical purposes we are forced to speak of the degree of 
accuracy rather than of accuracy itself. "Precision" is a 
shorter term than "degree" or "rate of accuracy," and 
means the same thing. Consequently precision is a per- 
centage of the measurement. Thus, the precision of Swed- 
ish gage blocks is stated as, say, one hundred thousandth of 
an inch per inch of length; and, strictly speaking, we should 
always state precision in that form. The attitude of the 
physicist toward these terms is : 

When the true value is known the ' ' Accuracy ' ' may be expressed 
as the difference between the experimental quantity obtained and 
this true value. Since, however, the exact or true value is seldom 
known, the accuracy of the result cannot be stated, and it becomes 
the more imperative to have methods of estimating the precision 
measure or reliability of the result of a series of observations. 4 

Precision of Workmanship 

Now, just as there is a limit to the precision of measure- 
ment for any given situation, so is there a limit to the pre- 
cision of workmanship that is possible for any given process 
or operation. And this limiting precision in manufacture 
follows after and is dependent upon the attainable precision 
of measurement of the work produced by said process, 
whether the measurement be made by a highly developed 
instrument or by mere visual comparison with a standard. 
What is true of the possible precision is equally true of the 
precision that it is sensible to use commercially, for cost will 
enter as the determining factor in the selection of the degree 
of accuracy best suited to a particular case. It is usually 
true, however, that a decidedly higher precision can be 
obtained with little effort, if the effort is properly made. 

Whether the attempt to increase precision should be 

4 " Precision of Measurements," by Professors George V. Wendell and W. L. Severinghaus of 
Columbia University. 



226 THE CONTROL OF QUALITY 

made is a matter of business judgment, and calls for a sen- 
sible decision. A military gun stock demands much closer 
fidelity to accurate dimension than does wooden furniture, 
but it would save a deal of profanity if desk drawers did 
not stick. The stores are full of all kinds of goods that indi- 
cate the same situation. It is a mistake to say that any- 
thing is good enough, for there must be some one dimension, 
for example, that is best suited to any special case. If the 
article, as designed, is best suited to the job, the manufac- 
turer's constant endeavor should be to obtain a closer and 
closer adherence to this ideal standard. This means the 
refinement of manufacturing through the reduction of errors 
— an undertaking that should be inaugurated by a study of 
errors themselves. 

The Theory of Errors 

The most valuable thing to realize about errors, so it 
would seem, is that they always have a tendency to occur. 
They follow the general rule that it is easier to be bad than 
it is to be good. Their number can be reduced only by the 
vigilant use of foresight, care, and thoroughness. More- 
over, like a snowball rolling downhill, they tend to 
accumulate others of their own kind; so that an ounce of 
prevention is worth many pounds of cure. 

A knowledge of the theory of errors is so important in 
accurate physical measurements that considerable atten- 
tion has been given to it, and several substantial literary 
contributions have been made. The application of their 
conclusions are too much confined to the physics laboratory, 
however, and should be more generally understood by man- 
ufacturers. The physicist starts off by making a distinction 
at once between mistakes — that is, mere blunders— and 
errors. In the factory, mistakes are the order of the day, 
and their best prevention lies in the direction of checks by 



MEASUREMENT AND ERRORS 227 

independent methods of one sort or another, as has been 
indicated early in this work. 

Individual vigilance and the habit of doing everything in a 
careful and orderly manner are the only means of reducing such 
inaccuracies to a minimum. It is often highly advisable to run 
some rough independent check experiment or to test the final re- 
sults with common sense to see that no gross blunder has been 
committed. 5 

Professor H. M. Goodwin, in his "Precision of Meas- 
urements and Graphical Methods," classifies errors as deter- 
minate errors, whose value can be determined and their 
effects eliminated, and indeterminate errors. He classifies 
determinate errors as: 

1. Instrumental errors, due to faulty adjustment or 

construction of the measuring instrument. 

2. Personal errors, due to the "personal equation" of 

the observer. 

3. Errors of method or theoretical errors, due ordinarily 

to using an instrument under conditions for which 
its graduations are not standard or correct. 

It will be observed that some errors lead to incorrect con- 
clusions, in spite of the fact that several measurements may 
be in agreement. Thus if the instrument is out of adjust- 
ment, or if the observer is, by nature, generous in his read- 
ings, so that he constantly errs on the high side of the 
measurement, or if the instrument is standard at 68° F. 
but is used at 90 F., the measurements may in all cases 
agree and still all be in error. 

As to indeterminate errors — accidental or residual — 
Goodwin says: 

Experience shows that, when a measurement is repeated a 
number of times with the same instrument and by the same observer 



5 " Precision of Measurements," by Professors George V. Wendell and W. L. Severinghaus 
of Columbia University. 



228 



THE CONTROL OF QUALITY 



under apparently the same conditions, the results usually differ in 
the last place or sometimes last two places of figures. Thus in so 
simple a measurement as the determination of the distance between 
two lines with a scale graduated in millimeters, successive measure- 
ments' will not agree to one-tenth millimeter if fractions of a milli- 
meter are estimated by the eye. 

Such errors have been found to follow the law of chance, 
which may be plotted graphically, as shown in Figure 53, 
from the equation: 



y=^=e hx 
Vtt 

in which y is the frequency of occurrence of an error of 
magnitude x, h is a constant related to the reliability of the 
observations and called the "precision index," e is the Na- 
perian logarithmic base (2.7183), and tt is the constant, 
3.1416. 

It will be observed from the curve that: 

First — Small errors occur more frequently than large ones ; 
Second — Very large errors are unlikely to occur; 
Third — Positive and negative errors of the same numerical 
magnitude are equally likely to occur. 




Figure 53. Probability Curve, Showing the Frequency of 
Occurrence of an Error 



MEASUREMENT AND ERRORS 229 

When Theory and Practice Differ 

This law assumes an infinite number of observations, 
but is reasonably true in most cases for a comparatively 
small number — hence its value as a guide. It presupposes, 
however, that the observer is trying to attain absolute accu- 
racy as nearly as may be; and, in the case of factory work- 
manship, this is where practice frequently departs from 
theory. Being sane, the workman will do what he believes 
to be to his own best interest. Consequently if there is a 
penalty attached to spoilage of work, he will deliberately 
keep on the safe side, since in that way he has a chance to 
repair his errors. 

Consider for a moment the case of a 2 -inch shaft which 

has a tolerance of .0004 inch. If the limits are set ' 

o 

inch (i.e., allowed .0004 inch over and o under dimen- 
sion) the greater part of the work will hug 2.0004 inch, 
because the operator will stay on the safe side and work 
toward the full dimension. If that is what is desired, well 
and good; otherwise the tolerance should be split up to 
allow for this tendency. In closer work especially, it would 

be better practice to set the limits as inch instead 

.0002 

.0002 . , . n _, , , •,- r 

of inch, or ± .0001 men. Ihe probability and 

o 

chance would thus favor securing more work to the desired 
ideal of 2.0000 inch. 

If all errors were equally distributed as to size and occur- 
rence, plus or minus, they would cancel each other to a large 
extent. In the factory they do not do so, but accumulate 
too rapidly for comfort. There are several ways in which 
this occurs, and happily there are several ways to meet the 
situation. 



230 THE CONTROL OF QUALITY 

The Chain of Inaccuracy 

W First, there is what may be termed a "chain of inaccu- 
racy" due to slip in the transfer of measurements. The 
master or reference gage is not quite like the model, the 
reference gage template is not quite like the gage, and so on. 
This error is negligible when a very precise method of 
measurement is available for checking purposes. 

The Chain of Wear 

Then there is a chain of wear, resulting in systematic and 
progressively increasing error. Granting the availability of 
more precise control apparatus, the remedy for such errors 
also is checking with sufficient frequency. As to the me- 
chanical side of intentionally lessening wear, there is room 
for considerable discussion and the resulting conclusions are 
widely applicable — to tools, to measuring devices, and to 
the product itself. Professor John E. Sweet was the great 
apostle in this field as in many other practical problems. 
In 1876 or before, he advocated the use, and pointed out the 
advantages of equal length wearing surfaces; viz., the first 
"straight-line" engine had a cross-head and guides of equal 
length, which, after years of use, showed practically no wear. 
In 1903, he stated, " Things that do not tend to wear out of 
true do not wear much." This principle is worthy of much 
consideration. In connection with it the present tendency 
toward the use of gages with wider and larger anvils — or 
gaging points — may be noted although it is true the use of 
such gages is to be attributed in part to other causes than 
minimum wear, inasmuch as they tend to give more accu- 
rate results, by lessening the chance of applying the gage at 
an angle. 

Incidentally, it may be noted that we may profitably 
extend the above principle to include the idea of even wear 
for a number of like parts. Thus if everything wore at the 



MEASUREMENT AND ERRORS 23I 

same rate, progressive errors would accrue, but their effect 
would be less, due to the averaging process going on, and 
thus tending to hold to uniformity. Take a multicylinder 
automotive engine — if one of the several piston gudgeon 
pins is a poor fit, all will tend to wear out of adjustment. 
Suppose, even, that all the pins are fitted with beautiful 
exactness by hand-reaming, but that some are larger than 
others. Will they wear evenly? Will they continue to re- 
main in adjustment as perfectly as if all were almost exactly 
alike? Furthermore, not only does the idea of even wear 
bear upon this matter of uniform dimension, but also upon 
the question of uniform hardness, uniformity of material, 
quality of finish, and so on. 

The Cure for Errors 

The cures for most errors will suggest themselves as soon 
as a systematic effort is made to locate and determine their 
causes. Whenever possible they must be hunted down and 
stamped out at the source. Some errors may be reduced 
by putting processes under uniform control, and in particu- 
lar by averaging the errors through spreading them out 
evenly. The experience of Whitworth in creating the first 
accurate surface plate reveals a valuable lesson. Taking 
three plates, alternately comparing them by contact, and 
then scraping off the high spots, he used the errors to de- 
stroy each other and thus created the basis of all our machine 
shop precision — a true plane surface, relatively speaking. 

The concluding observation to be drawn from the study 
of measurement and of errors, beside the very obvious neces- 
sity for care and thoroughness as to every detail, is the need 
of providing control apparatus for the qualities with which 
we are concerned. To be effective, such apparatus must 
be safeguarded, and even then it is useful only in so far as its 
use and the conditions surrounding its application are freed 



232 THE CONTROL OF QUALITY 

from possible causes of error. The ideal dimensional con- 
trol center or dimensional laboratory to be described in 
Chapter XVII, is to be considered as a guide to what, in 
principle, any such control laboratory should be, regardless 
of the quality concerned. Dimension has been chosen as 
the type merely because dimensional control has been car- 
ried to a higher degree of precision and its apparatus is more 
highly developed than is the case with most other qualities 
— such as color, for example. This condition, it seems prob- 
able, will be modified as time goes on, and more and more 
qualities are brought to the same state of accurate control. 6 
The fact that means do not exist at the moment for 
measuring some of the characteristic qualities with which 
industry is concerned, merely serves to indicate the direc- 
tion in which the start should be made toward conscious 
improvement of these qualities. If industry makes the 
demand on science to develop principles, practices, and 
equipment to meet its requirements, the needful things that 
are lacking at present will be supplied. 

6 The principle of measurement, in fact, is being extended to evaluate the functions of 
management. See an editorial by L. P. Alford in Management Engineering, Nov. 192 1. 



CHAPTER XIV 

QUALITY DEFINED— THE IDEAL STANDARD 

Characteristic Qualities of Product Must Be Known 

Thus far we have considered the subject of quality in its 
various relationships and have traced the basic influence of 
measurement in order to prepare the way for a better under- 
standing of quality itself. We are now in a position to ask 
— "What is it that constitutes quality?" 

The first answer is that each attribute or characteristic — ■ 
shape, dimension, strength, finish, color, and so forth — 
which defines one kind of article is a quality of that article. 
The more definite and specific we make the descriptions of 
the dominating qualities, the more accurately do we under- 
stand just what the product is intended to be, and, inciden- 
tally, wherein it is to differ from other articles of the same 
general class of goods. To state a quality at all accurately, 
it must be compared with some arbitrarily selected standard. 
For example, we might say a rod is to have length, but we 
have not described the rod as regards dimension until we 
state the relationship between its length and that of some- 
thing else. We can secure a more exact definition of the 
dimensional quality of the rod if we say that its length is to 
be the same as that of a sample rod which has been selected 
as standard. But, as a matter of fact, in this case the 
comparison would be made with the well-accepted standard 
of dimension and the length stated in standard units of feet, 
inches, or both, depending on convenience. 

This well-known and seemingly elementary example is 
simple only because we have a thoroughly established and 
well-known method of comparison or measurement for 

233 



234 THE CONTROL OF QUALITY 

dimensional quality; but what about some of the other 
qualities? With respect to color, for instance, there is, as 
yet, no accepted method of analysis and comparison with a 
standard. To say an article is to be painted red is nearly as 
loose a definition of color quality as to describe dimensional 
quality by saying that a rod had length — because there can 
be an enormous number of tints and shades of red. In the 
absence of a color scale for numerical comparison, we are 
reduced to saying that the color will be like a given standard 
sample. We must also take precautions to see that the 
color of the sample itself does not change in the course of 
time, and thereby carry the product away from the standard 
as originally set. 

The question of whether such qualities as color can be 
reduced to a basis of definite measurement with the same 
ease of treatment as dimension must be deferred at this 
time. Meanwhile, dimension will be used chiefly to illus- 
trate the discussion as it proceeds. It should be borne 
in mind, however, that the general principle applies to the 
treatment of all qualities, that no quality can be described 
without comparing it to some standard — which process is 
measurement — and that the application of the idea of meas- 
urement must not be confined to dimension alone. This is 
one excellent reason why every industrial executive who 
is interested in the subject under discussion should be 
familiar, in a general way at least, with the principles under- 
lying the precision of measurement and the theory of errors 
— to secure an important attitude of mind and a necessary 
sense of discrimination, of proportion and perspective. 

Quality Varies Continually 

One of the first things that this knowledge will reveal is 
that there is no such thing as an absolutely accurate measur- 
ment. No matter how carefully the unknown is com- 



QUALITY DEFINED— THE IDEAL STANDARD 



235 



pared with an accepted standard, errors are bound to creep 
in; and very shortly a certain critical point is reached be- 
yond which these errors can be reduced only through the use 
of extreme precautions, if at all. 

This thought leads at once to one of the most important 




Figure 54. 



Checking Johansson Adjustable Limit Plug Gage with Gage 
Blocks Mounted in Holder 



conceptions of what constitutes quality, an idea that must 
be kept in mind throughout the subsequent study of the 
control of quality, namely, that quality is a variable. 
Quantity relates to the product en masse, and in this sense 
is abstract and impersonal. Quality, however, is different 
for each separate article produced. Hence the quality of 
the factory product varies from piece to piece. This fact 
must be clearly appreciated before an attempt is made to fix 



236 THE CONTROL OF QUALITY 

upon the standards of quality desired, or to take up the con- 
sideration of the organization and arrangement of manu- 
facturing equipment and methods most suitable for securing 
these desired standards with greatest economy. In prac- 
tice, the degree of quality varies continually from the 
standard desired. Further, the degree of quality varies 
with respect to time, in the sense that the attempt to make 
many things alike results inevitably in quality gradually 
slipping away from this desired standard as the work pro- 
ceeds. This tendency of quality in all its forms to vary and 
change is always present as a potential force, and acts ex- 
cept in so far as it is held in check by external means pro- 
vided for control purposes. 

Development of the Design 

With the preceding in mind, it should be apparent that 
the study of the control of quality must begin with an in- 
tensive study of the product, from which should result what 
is ordinarily called the "design." Now the production of 
almost anything, let alone making accurately uniform arti- 
cles, presupposes a definite standard, usually represented by 
drawings, specifications, or a model; but preferably by all 
three. This standard is purely ideal and cannot be repli- 
cated exactly in quantity, because the absolute is unat- 
tainable. Nothing ever was made in exact accordance with 
the ideal design, or ever will be. 

Under given conditions, the time and cost of production 
in quantity varies with the degree of accuracy to the ideal 
standard that is required. Hence the art of the designing 
engineer and of the production engineer is called into play to 
fix upon manufacturing standards, which vary from the ideal 
by certain differences or allowed errors. This process sets 
limits which constitute a tolerance for the actual fabrication 
of the work. Returning to the example of the rod, the com- 



QUALITY DEFINED— THE IDEAL STANDARD 237 

plete design would state its length as so many inches plus or 
minus certain stated limits, or allowable errors. 

By way of summary, suppose now that we reverse the 
preceding order for the purpose of more clearly developing 
the following definitions : 

1 . The complete design (which will be referred to simply 
as the "design ") is the exact description of the product, and 
therefore sets forth in detail (with allowed variations from 
exact measurements) the characteristics of all essential 
qualities, i.e., the manufacturing standards. This pre- 
supposes, of course, that the product has been thoroughly 
analyzed and that a list of the desired quality characteristics 
has been made. 

2. The "ideal standard" is the bare design without the 
allowed variations, and consequently is merely the outline 
or shell of what the ideal product would be if quality were 
not a variable. 

3. The "theoretical standard" is what the ideal stand- 
ard would be if it were designed with a view solely to obtain- 
ing the best article for the purpose for which the product 
is intended without regard to cost; i.e., it is the 100 per cent 
standard for the class of articles to which the product be- 
longs. 

It is hardly proper to call these concepts by the formal 
name of "definitions," as they have no special significance 
except as a means of avoiding misunderstanding of the 
following consideration of some ideas about design that are 
essential to our purpose. 

The Theoretical Standard 

The principal value of the theoretical or 100 per cent 
standard, to which attention was directed in Chapter II, is 
to provide something to which we can refer in improving the 
product, as time goes on and such improvements are com- 



238 THE CONTROL OF QUALITY 

mercially practicable. The latter are always desirable, if 
the selling price is not increased thereby. The manufac- 
turer who has a well-rounded out idea of what his product 
would be if it were the ioo per cent article of its class, is 
better able to guide future progress, also to know in what 
directions such progress should take place. Incidentally 
he may avoid the predicament of the modest advertiser who 
illustrates a "perfect" product, only to announce incon- 
sistently with each new season, an improvement of an al- 
ready perfect thing — and this to a purchasing public which 
is becoming increasingly critical and whose discrimination 
is ever more intelligently applied. 

No mention has yet been made of one of the greatest ad- 
vantages in having a theoretically perfect standard to guide 
the development of a design — namely it will help to coun- 
teract the danger of copying the errors of the past, by 
blindly doing things as they have been done before. 

Professor John E. Sweet 1 expressed the idea as follows: 

Whoever designs a new machine or an improvement on an old 
one conceives of some feature or ruling object of his design or some 
feature that is an improvement on present practice and neglects the 
other features — simply follows common practice without consider- 
ing whether the other features may not be as open to improvement 
as the special feature he is working out. . . . And it all comes 
from following habit, without reason ... it is only those who 
come to think of the best way who are likely to do the best; and 
those also who think that the "best way is bad enough." 

It happens too often that betterment of the product is 
blocked by prohibitive cost, simply because the designer 
either was not informed as to the probable direction such 
improvement would follow, or failed to take it into consider- 
ation in designing earlier models. With a wider and 
farther-seeing perspective, he would have been able to shape 



'John E. Sweet, "Things That Are Usually Wrong.' 



QUALITY DEFINED— THE IDEAL STANDARD 239 

his design and make his factory arrangements so as both to 
meet the present needs and to be adapted readily for an im- 
proved product when the time is ripe for such refinement. 

The Ideal Standard 

The outline or skeleton design, without statement of the 
permissible variations, is here called the "ideal standard" 
— it is ideal in the sense that it cannot be realized exactly in 
practice in spite of the fact that it is the desired standard. 
As a matter of fact, one article might be made so very 
nearly like the ideal that the errors could not be detected by 
the available means of measurement, but its cost would 




Figure 55. Use of Johansson Gage Blocks and Sine Bar to Check Taper of a 
Milling Cutter Shank 



240 THE CONTROL OF QUALITY 

place it beyond the pale of commercial possibilities. A 
great telescope is an example of the sort. But the construc- 
tion of two such articles alike to the same degree of exactr 
ness would markedly increase the effort required, even if it 
were possible. The manufacture of many such articles 
would increase the problem enormously, and any attempt 
to avoid errors wholly would certainly fail. On the other 
hand, a relatively slight releasing of the requirements for 
accuracy renders the task much simpler, so that it becomes 
a true manufacturing proposition. In fact it is possible to 
set a very high standard, provided the conditions of the 
problem are appreciated and proper precautions taken at 
the start to meet them. 

To admit that the ideal or desired standard cannot pos- 
sibly be realized, may at first appear like an attitude of 
hopelessness, but that is not the fact. All progress requires 
that we have in mind some rather definite ideals, which we 
are trying to realize. It detracts in no degree from the im- 
portance of the effort to realize these ideals, if it is admitted 
that at best it will result only in approximation to them. 
The fact remains that before we attempt to make anything, 
we should know what we are trying to make ; and however 
thoroughly we may know this ourselves, it is equally im- 
portant that we describe it so clearly that all concerned in 
the work may know what we wish done. The more def- 
inite, exact, and complete this preliminary description 
which makes up the skeleton design, the greater will be the 
economy of effort, materials, and time in the work of con- 
struction. 

Progress Toward More Exact Designs 

The increasing tendency toward the more specific 
and complete definition of qualities is easily traced. It is 
not necessary to hark back very far in the development of 



QUALITY DEFINED— THE IDEAL STANDARD 



241 



engineering to reach a point where the design was developed 
in large part as the work progressed. There is a quite 
credible story to the effect that early wooden shipbuilding 
was carried on in two stages of hull construction. The 




Figure 56. Set-Up of Johansson Blocks for Checking Taper of a Special Plug 

Gage 



shipbuilder first erected the parallel middle body, after 
which the construction of the bow and stern was taken up 
by a " bow-and-stern gang." Such a gang traveled from 
yard to yard, sized up the job as it stood, perhaps made a 
rough sketch on a piece of plank, and with this general 
understanding proceeded to erect a bow and a stern to 
suit the work already in place. This method certainly 



242 THE CONTROL OF QUALITY 

had the advantage of simplicity, to say nothing of reducing 
overhead expense. 

An examination of the early designs and construction 
plans in any of our oldest machine shops, shows nearly the 
same degree of rough-and-ready methods. There is much 
sad experience to be read between the lines in following up 
the evolution of the present-day drawing from its crude 
start, through the later addition of more and greater refine- 
ments, until we arrive at the finished plans of the modern 
highly organized drafting-room. Notice that the tendency 
is toward an ever-increasing exactness and completeness in 
showing the details of what is wanted. We have learned, in 
short, that it is cheaper to make our mistakes on paper than 
to have to correct them in the materials of construction as 
the work progresses. 

The same development is to be noted in the specifica- 
tions or written descriptions that supplement the drawings, 
although not to the same extent, for even today most 
specifications contain ambiguous language. The wise 
manufacturer, while preparing his estimates, will be careful 
to iron out as far as possible, before starting work, such ex- 
pensive little pitfalls as "small surface scratches on this 
part will be permitted in the judgment of the inspector," or 
"variations in other dimensions will be allowed, but the 
work must be to the purchaser's satisfaction." 

Changes in Design Must Be Avoided 

This lesson of past experience in design and manufac- 
ture has been paid for dearly. It teaches quite clearly that 
the time to make up our minds, as well as to do a lot of 
thinking, is before commencing to make chips. But even 
with the full knowledge of this principle before us, is it 
rigorously applied? In the majority of enterprises it is not 
so applied, and the particular way in which it is violated 



QUALITY DEFINED— THE IDEAL STANDARD 243 

most seriously may be summed up by the word ' ' changes ' ' 
— the great killer of economy in manufacturing, whether it 
be of ships, automobiles, firearms, or what-not. 

The design should be made with an open mind and the 
designer given the widest latitude while he is designing. 
Further, a method of attack has been indicated that 
should make future changes in the details of the design a 
matter of orderly development and progressive improve- 
ment. Curiously enough, however, this freedom of action 
must later give way to its exact opposite. Once the design 
is completed and manufacturing started, the designer must 
"sit tight: 1 

Usually the production man himself is alive to the 
serious delays and losses caused by changes in design made 
after production has begun; but ordinarily the changes 
originate from a source outside of the shops. Improve- 
ments in design are rapid, and the temptation is great to 
make changes that better, or seem to better, the product. 
Consequently after all the trouble of getting out carefully 
detailed plans, after making manufacturing arrangements 
to carry them out, and even after material is in process, a 
rumor comes into the shop that such and such a thing is to 
be changed. The result is uncertainty and the beginning of 
confusion. Then comes the order for the change, which is 
usually made without the degree of care that was used in 
presenting the original design, for as soon as the making of 
changes begins, many ill-considered changes are suggested. 
The general effect, then, is to mix experimental work with 
production, instead of separating it out of the routine manu- 
facturing shops as is done in any well-regulated factory. 

When Improvement Changes Should Be Made 

Some years ago in a large plant making a high-grade car, 
changes in design were being made with such frequency that 



244 THE CONTROL OF QUALITY 

the effect on production finally demanded the installation of 
a special system for handling these changes. It is true that 
the art was moving forward with rapid strides. Without 
doubt business considerations warranted the prompt adop- 
tion of some of the new improvements. On the other hand, 
the model was changed formally each year, and most of the 
improvements should have been collected systematically 
and saved for incorporation in the next season's car. The 
chief engineer, however, was busy improving the car from 
day to day, while the factory output was unnecessarily 
slowed down and the work made much more costly to the 
purchasing public. 

It is frequently a matter of considerable doubt whether a 
radical change in appearance is advisable, even when the 
change is made for the ostensible purpose of modernizing 
the design. A "quality" article, for example, has been 
developed in accordance with an ideal — otherwise it would 
not be high grade. In the course of time, it acquires in the 
eyes of its friends a distinctive but often intangible some- 
thing which makes it different and gives it a distinctive 
character. The time inevitably comes when there is a 
temptation to bring the design up to date, but long before 
the attempt is made, the necessary changes should be 
mapped out along lines consistent with the basic ideal of the 
design. Then the product can be modernized gradually 
without losing the resemblance to the original which is as- 
sociated with a reputation for satisfaction. The ideal on 
which the design was made and on which the success of the 
business is founded should never be destroyed. 

Every Cause Has Several Effects 

Some changes must be made. In such cases the greatest 
care and attention should be applied to see that they are 
put into effect so gradually as not to interfere with efficient 



QUALITY DEFINED— THE IDEAL STANDARD 245 

production any more than is absolutely necessary. It be- 
comes the duty of the production man to impress that fact 
strongly upon the designer. Very often the fact alone must 
be accepted, because the sources of loss are so intimately 
interwoven with the processes of production that separating 
them out is too difficult to be worth while. It is a perfectly 
safe statement that any change costs money in an amount 
entirely out of all proportion to the direct work involved. 

Finally, there comes to mind the principle laid down by 
Herbert Spencer — "Every cause has more than one effect." 
You may accomplish a slight local improvement, but you 
should not forget that you have altered other conditions as 
well. The very thing that improves one part of the design 
may affect other parts adversely. 

Precautions to Avoid Changes 

Changes in work due to errors in design are almost bound 
to occur, but every effort should be made to minimize them. 
Careful work in the drafting-room will decrease such errors. 
In small accurate work it is often helpful to make drawings 
to a magnified scale, or even to make a large-scale model. 
Many engineers hold that our drafting-room practice has 
reached such a degree of perfection that the making of a 
model is unnecessary. There are some cases, however, in 
which a model would seem to be advisable, if for no other 
reason than to assist the draftsman's eye to a more readily 
comprehended picture of the relations of the component 
parts in a complicated assembly. 

Further, in every sort of work which permits of making a 
model or sample, it should be noted that every practicable 
effort should be made to avoid changes occasioned by mis- 
takes in the designs, by the obvious process of eliminating 
the necessity for such changes before beginning manufactur- 
ing operations. The way to discover and eliminate the 



246 THE CONTROL OF QUALITY 



ORDER FOR CHANGE IN DRAWING 

Operation Mark Date 

Tool Name 

Description of Change 



Reason for Change. 



Preliminary Action by Order Dept. on Outstanding Orders 

Final Action by Order Dept. (taken after completion of change) 



Drafting Room to check details of other tools that may be affected 
by the above. 

Suggested by — Approved 

Classification of Change Accepted 



Copies to 

Process Engineer. 
Chief Draftsman. 
Order Superintendent. 



Figure 57. Order for Change in Drawing 
Form used at Remington armory, Bridgeport. 



QUALITY DEFINED— THE IDEAL STANDARD 247 

' ' bugs " in a new design of product is by careful and thorough 
work in the experimental and research department. The 
latter department will pay for itself many times over by 
providing a smooth path of development and co-ordination 
between the engineering department and the producing 
shops. Without this procedure, experimental work, which 
has to be done somewhere by someone in any case, is 
mixed with production, and the resulting great waste is 
quite likely to be lost sight of because no ordinary cost or 
production system will reveal it. 



CHAPTER XV 
THE WORKING STANDARDS 

The Compromise in Setting Tolerances 

Granted that the ideal standard cannot be realized in 
practice because quality varies continually, practical manu- 
facturing or working standards must be determined. These 
vary from the ideal standard by certain differences or allowed 
errors, and by adding them to the outline design or ideal 
standard, a complete design is obtained. 

The use of the plural in referring to the working stand- 
ards is intentional, since many differences from the ideal 
design will occur in the shops, and from these must be se- 
lected the variations that are to be allowed in the finished 
article. This process of selection will fix the working stand- 
ards. Needless to say, the determination of permissible 
errors or variations is not always a simple matter, but rather 
a task calling for the exercise of unusual discrimination and 
good judgment. The designer, especially when freed from 
responsibility for costs, will endeavor to have these varia- 
tions as small as possible. He will insist on a close approxi- 
mation to the ideal. On the other hand, the man who is 
responsible for production will reason that the time and 
cost of manufacturing under certain conditions will increase 
with the degree of accuracy required; so he naturally will 
seek to obtain the largest possible allowed errors. 

If the situation is dominated by either of the above- 
mentioned views, trouble is very likely to ensue. The unre- 
stricted designer usually demands unnecessarily high stand- 
ards, government work sometimes furnishing an extreme 
example. Contrariwise, the unrestricted production man 



THE WORKING STANDARDS 249 

usually tends too strongly in the opposite direction. As is 
usual in such cases, the truth lies somewhere between the 
two extremes; hence the necessity for someone to apply 
good common sense in the selection of the working stand- 
ards. The best compromise is to be had, usually, when the 
standards are selected by a well-balanced committee on 
which engineering, production, and inspection are repre- 
sented. 

Raw Material Standards 

The design states the kind of material from which a part 
is to be made, and specifies the required conditioning of the 
material (such, for instance, as heat treatment), also the 
dimensions and form desired, the finish of the surface, and 
frequently the requirements to be met in assembling and 
functioning in service. 

The selection of suitable raw material is a matter of the 
utmost importance, in which the governing considerations 
are uniformity, ability to meet service requirements, and 
ease of working in the manufacturing process. First cost is 
a subordinate consideration in nearly every case, in com- 
parison with uniform behavior in manufacturing and uni- 
form performance under working loads. A typical instance 
is furnished by the motor industry, where a very low-priced 
car has been built of the highest percentage of alloy steels. 
There are better places for economy than in the raw 
materials. 

The determination of working standards for raw ma- 
terial has received a great deal of attention in recent years 
and need not be dwelt upon here. The preparation of 
standard specifications for various kinds of material (and 
for the different grades of each kind) by some of the great 
railroads and manufacturing plants, by various governmen- 
tal departments, and by the American Society for Testing 



250 THE CONTROL OF QUALITY 

Materials, has made available a large body of technical 
data arranged in systematic form. It is only necessary to 
select the specifications of a suitable material in order to 
have the limiting conditions known. 

In the case of metals, especially, the data are quite com- 
plete. The permissible variations in the chemical constit- 
uents are set forth, together with the limiting conditions 
for pertinent physical characteristics. In the case of other 
kinds of material, the essential characteristics are mentioned 
and limits frequently stated. It would seem, however, that 
much progress remains to be made in specifications for many 
of the usual non-metallic materials, such as wood and fibrous 
materials, principally in the way of information to be 
collected and systematized through the application of the 
microscope and the binocular microscope and other scien- 
tific apparatus not applied as yet to any great extent in such 
work. The use of micro-photography in the metallographic 
study of metals has developed a wide and fruitful field. A 
similar development will follow the application of these 
methods to many of the non-metals. 

Conditioning Standards 

The determination of working standards for what, for 
lack of a better term, may be called the "conditioning of 
material" is not so simple a matter. A part made from 
soft or untreated steel in order to permit economical ma- 
chining or working, subsequently may require some form 
of hardening or tempering in order to suit it to the duty it 
must perform in the assembled mechanism. In fixing the 
limiting conditions the scleroscope or Brinnell test is 
available, or perhaps a file test may answer. Another ele- 
ment is introduced, however, if appreciable distortion 
occurs in individual parts to such an extent as to require 
straightening. If straightening is necessary and the func- 



THE WORKING STANDARDS 251 

tion.of the component part is an important one, some sort 
of special test should be specified, of a kind to demonstrate 
that the part will pass the maximum demands that are likely 
to be encountered in service. 

Important springs should have maximum and minimum 
weighing tests to be made in a special fixture, and should be 
set up for a specified period of time and to a given displace- 
ment without more than an allowed set. 

The time and order or the particular stage of manufac- 
ture at which any such special tests should be applied may 
possibly be of importance, hence the value of listing these 
tests on operation sheets and route cards, just as if they 
were ordinary manufacturing operations. Special tests 
should be provided for important non-metallic materials 
requiring special treatment or conditioning prior to or dur- 
ing manufacture. The kiln drying of high-grade lumber is 
a case in point, where the binocular microscope may some- 
times be used to advantage. 

Standards of Finish 

There is considerable laxity in determining standards for 
exterior finish. Probably the fact that more attention is 
not devoted to setting standards of finish is due as much to 
commercial considerations as to the difficulty of reducing 
the degree of finish to measurable and tangible terms. The 
manufacturer selects a finishing process sufficiently econom- 
ical for the purpose, and then strives to get as good a finish 
with that process as is reasonably possible, on the general 
assumption that the shinier or prettier an article looks the 
more it will appeal to the customer's eye. Unfortunately 
there often is good reason for this attitude, many purchasers 
prefering a polished surface where a good coat of paint over 
a rough surface would be more durable and less expensive to 
maintain. In competitive businesses, however, it is often 



252 THE CONTROL OF QUALITY 

wise to give the purchaser what he thinks he wants, even if it 
may not be the best thing for him. Note, for example, the 
face of a pressure valve flange. It has been faced off in 
the lathe with a roughing cut, followed by at least one finish- 
ing cut. Then one or two small circular grooves are cut for 
the gasket to be squeezed into, in order to secure tightness. 
And yet one rough turned facing would accomplish the pur- 
pose better by providing a multitude of grooves. This is 
only another instance of perpetuating the errors of the past 
by thoughtless imitation. 

Oftentimes the allowable gradations in the hue, shade, 
or tint desired for a colored surface are left to the judgment 
of the production man or the inspector. Sometimes a sam- 
ple is furnished which is to be approximated as nearly as 
possible commercially. In such cases, it is well to obtain 
the advantage of manufacturing to limits by providing 
samples showing all extremes that will be allowed. When 
standards for smoothness of finish are to be set, the same 
practice should be followed, i.e., the use of standard samples. 
Preferably a few sample parts should be used for small work, 
some showing acceptable work, and others showing work not 
quite good enough to be passed. In other words, the sam- 
ples should be selected close to the limiting conditions 
desired. This general process is the best that can be 
adopted until more and more of such qualities are reduced 
to a basis of numerical measurement — a result that is sure 
to come as the qualitative refinement of our industries 
progresses. 

Standards of Dimension and Form 

In its ultimate effect the establishment of practical or 
working standards for dimension and form covers the most 
important and far-reaching subject of all. It is of the es- 
sence of that great branch of repetition work which is known 



THE WORKING STANDARDS 



253 




254 THE CONTROL OF QUALITY 

as "interchangeable manufacturing," which will be consid- 
ered in greater detail in the following chapter. 

In determining the working standards for dimension and 
form or shape, the relation of each part to the other com- 
ponent parts of the mechanism must first be considered. 
The ideal standard, as described in the preceding discussion, 
fixes one size and shape, and it may be assumed that the 
designer in articulating the mechanical movements involved 
provided for the necessary strength and other physical 
qualities required. These qualities have to do with what 
might be termed the "main body" or "interior" of the 
parts, whereas for present purposes we are concerned with 
variations in the outer surfaces or exterior of a given part, 
with special reference to the similar surfaces of the other 
parts of the mechanism with which the given part works. 
We know that these outer ends of the dimensions, so to 
speak, are going to vary, and therefore we must determine 
the limiting variations in the fit of the one part to the 
other parts that will still secure a proper functioning of the 
entire mechanism. In this way we can settle upon the 
greatest distance from edge to edge of related parts, as well as 
the smallest separation or play that is permissible, thus de- 
termining the maximum and the minimum allowance for fit. 

With the figures just referred to as a guide, the next 
step involves the determination of the permissible variations 
in the dimensions of each part, considered separately, and 
these maximum permissible variations fix the limits of the 
dimensions, the difference between any set of limits being 
known as the "tolerance." 

Allowed Variations Denned 

The terms "allowance," "tolerance," and "limits" 
have long been a part of the technical nomenclature of 
repetition and interchangeable manufacture, but are only 



THE WORKING STANDARDS 255 

recently beginning to receive the detailed study they merit. 
It is not the purpose of this book, however, to do more than 
trace their application in the development of working stand- 
ards of dimension, as a resultant of the basic idea that 
quality is a variable. 1 . 

The following definitions are taken from the "Progress 
Report of the Committee on Limits and Tolerances in 
Screw Thread Fits, to the Council of the American Society 
of Mechanical Engineers," as published in the Journal of 
that Society for August, 1918: 

Allowance — Variation in dimensions to allow for different 
qualities of fit. 

Tolerance — The allowable variation in size equal to the dif- 
ference between the minimum and maximum limits. 

Limits — Two sizes expressed by positive dimensions, the 
larger being termed the maximum, and the smaller, the minimum 
limit. 

In some cases, as in mating threaded parts, or in moving 
parts which must not touch each other (such as in turbines, 
pumps, and so on), an actual clearance must be provided 
for. 

Clearance — A difference in dimensions, or in the shape of the 

surface, prescribed in order that two surfaces, or parts of surfaces 

may be clear of one another. 2 

The opposite situation arises in certain cases, when parts 
are fitted with a "pinch." 

Necessary Precautions 

The process of working from the allowance to the 
determination of tolerances and limits involves a nice ap- 
plication of judgment (both to the theory of the design and 

1 For an interesting discussion of this subject the reader is referred to a paper on "Gage Limits 
in Interchangeable Manufacture," by Colonel E. C Peck in the October, iqiq, issue of Mechani- 
cal Engineering; also to some notes on the "Theory of Tolerances and Comparison of Symmetri- 
cal and Asymmetrical Systems," {Ibid., July, 1910), together with a very practical comment 
thereon by J. Airey {Ibid., October, 1919). 

2 British Engineering Standards Association definition. 



256 THE CONTROL OF QUALITY 

to the current shop processes), which should consider es- 
pecially the following: 

1. The effect on the allowance for one dimension, of the 
errors accumulated from the variations in dimension of any- 
other mating part or bearing point, if any. For example, 
if we are determining permissible variations in the diameters 
of two mating gear-wheels, we must consider the effect of 
the play to be allowed in their supporting bearings. 

2. The effect of wear of the parts after the mechanism is 
in use in service. The tolerances should be proportioned to 
favor the parts that probably will wear most rapidly, with 
the object in view of insuring uniform and even wear. 

3. The relative difficulty of manufacturing the parts con- 
cerned. The parts should be favored whose manufacture 
involves the use of mechanical operations or processes that 
are the most difficult to hold to dimensional accuracy. 

4. The effect of wear of cutting tools, dies, fixtures, jigs, 
gages, or other special manufacturing equipment, in order 
to secure the greatest economy in their cost. The most ex- 
pensive equipment should be given the longest wearing life. 

The above process will give a set of limits for all im- 
portant dimensions of the finished parts only, so that a proc- 
ess, somewhat similar in principle, must be gone through 
with to determine similar limits for the vital dimensions of 
unfinished parts after each mechanical operation involved in 
the process of manufacture. 

If "close work," requiring a high quality of dimensional 
accuracy, is involved, it is specially important to consider 
the possible effects of errors accumulated from process to 
process. This suggests, at once, the importance of a well- 
worked-out list of mechanical processes to be used in making 
any given part, which list should show not only the sequence 
in which the work will be processed ordinarily, but also the 
alternative arrangements of operations that may be used in 



THE WORKING STANDARDS 



257 




Figure 59. Reading Inside Micrometers after Measuring Inside of Cylinder 
Brown and Sharpe Manufacturing Company. 



17 



258 THE CONTROL OF QUALITY 

case shop exigencies indicate the desirability of rearranged 
routings. In this way we are enabled to foresee what ac- 
cumulated errors may arise in the case of emergency changes 
in routing, and, being forewarned, to guard against them. 

The selection of locating and reference points is closely 
inter-related with the above. Working from holes provides 
a safe method when too much wear is not involved. The 
same scheme may often be simulated by the use of tempo- 
rary holes or by adding locating lugs which are cut away after 
they have served their purpose. 

It is sometimes desirable to minimize the effect of ac- 
cumulated errors by distributing them — a procedure known 
in precision of measurement as "solving the problem for 
equal effects," i.e., the errors allowed in each variable are 
calculated to give the same effect in the final answer. 

Dimensional Working Standards 

After the limits have been worked out, they should be 
shown as a part of the working drawings. If these draw- 
ings are then furnished to the shops as the final references 
for production purposes, they become the practical working 
standards for dimension, as the term is used herein. With 
highly skilled operators, working on processes inherently ac- 
curate, these plans may be all that is necessary. Where a 
relatively small number of parts are to be made, and es- 
pecially in large work, it would not be the part of good sense 
to supply the shops with anything in addition to the plans 
as the standards. In many cases all the information 
required may be set forth on the working drawing for the 
finished part, including both the limits for the finished work 
and the amounts of stock to be allowed for grinding, 
turning, and similar operations. 

In passing from the classes of work just indicated, to the 
quantity production of interchangeable parts of small size, 



THE WORKING STANDARDS 259 

we enter a field where economy of manufacturing indicates 
the desirability of increasingly specialized equipment, such 
as special cutting tools, holding devices, and gages. In such 
cases if working plans are supplied to the shops at all, it 
usually is best to do so only as a matter of information and 
to substitute for adjustable precision measuring instru- 
ments fixed-dimension gages of various sorts which have the 
limiting dimensions worked into them in physical form. 

It is safe to say that the next few years will see a great 
extension of the use of limit gages in American factories, 
with corresponding benefits as regards both quality and 
economy. The introduction of a gaging system, however, 
will cause new conditions to arise which will involve special 
problems peculiar to the system in question. It is a matter 
in which some very small things become paramount, and 
hence require the most careful and systematic attention, as 
will be discussed in a later chapter. For the present, at- 
tention is invited to the fact that when gages are used, as 
just stated, they constitute the working standards, and the 
plans cease to function as the working standards. 

It remains to be said, for completeness, that it may not 
be considered desirable in certain cases to incorporate, in 
the gages as furnished to the shops, the maximum limits 
that may be used while still assuring proper functioning of 
the parts after their assembly into the mechanism. This 
practice of making the shops work to closer limits than the 
inspectors are permitted to pass finds its justification some- 
times in a longer useful life for the gages. The practice, 
however, rests chiefly on the idea that it may help to reduce 
the losses in spoiled work by permitting the salvage of 
some of the parts that are bound to fall outside of the limits 
given to the factory, while also encouraging the cultivation 
of greater accuracy in the operators. . This savors somewhat 
of the theory of the traffic laws that have given rise to signs 

( 



260 



THE CONTROL OF QUALITY 




THE WORKING STANDARDS 261 

reading "Speed limit 15 miles," which one so often sees out- 
side small towns. The sign probably is put there in the 
hope that the motorist will reduce his speed to 25 or perhaps 
20 miles, depending on the degree of hopefulness of the 
authorities, but usually he keeps his foot on the accelerator. 
Now the machine operator will answer to the same psy- 
chological reactions if he knows there are two standards in 
use, unless and only in case conditions are so arranged that 
he is made to realize it as being to his best interest to stick 
to the limits given him. It may be necessary, in fact, to 
keep the larger limits a secret, which involves using them in 
a separate salvage department. As a rule, however, it 
would seem to be better practice, with the possible excep- 
tion of certain very special cases, to try for the same result 
by the more direct route of frankly making known the 
maximum permissible variations, and then taking proper 
precautions to safeguard these limits. 

Assembling Standards 

Theoretically, in strictly interchangeable work it should 
not be necessary to check up the fit of parts after they have 
been assembled, except possibly as an additional assurance 
that the constituent parts of the assembly are within the 
allowed tolerances. As a practical proposition, however, it 
is often advisable to provide for the verification of certain 
important functioning dimensions in subassemblies, as, 
for example, when parts are assembled on a tapering shaft, 
or where the effect of improper fits is multiplied by a long 
arm (as in the case of a long rod with a short bearing on one 
end, working under conditions that make side play of the 
other end of the rod undesirable) . In work made partially 
interchangeable, such assembling standards should be pro- 
vided for, by setting limiting dimensions for the assembled 
parts in the case of all vital dimensions. 



262 THE CONTROL OF QUALITY ■ 

Final Tests 

After the parts of the mechanism have been assembled, 
a final test, or series of tests, should be made, simulating the 
maximum demands to be made on the mechanism after it is 
placed in service. Strength tests are, in themselves, the 
maximum limit — an armature will spin at twice its rated 
speed without bursting, or it will not; a derrick will lift the 
specified overload without permanent set, or it will not; a 
gun barrel will stand a heavy proof charge without bursting 
or bulging, or it will not. Thus, in such tests there is but 
one limit. But, in many of the final tests and trials used to 
demonstrate standards of quality, the same idea of permis- 
sible variations in quality (expressed in terms of limits) finds 
application, whether these tests are to be applied to the 
complete assembly or to some subassembly. In the testing 
of the trigger pull of a rifle, for example, the limits may be 
set at given minimum and maximum pulls stated in pounds ; 
or the economy and the speed regulation of a motor may be 
demonstrated by trial to be within certain limiting per- 
centages. 

Final tests must be made under as nearly the same con- 
ditions as the mechanism will encounter in service when 
reasonably possible. If this cannot be done, the test con- 
ditions should always vary from service conditions in a 
known way and to the same degree, i.e., all mechanisms 
should be tested under like conditions. 

Recapitulation 

Working from the theory that quality is a variable, and 
hence that the ideal standard or design cannot be reproduced 
exactly, the conclusion is reached that practical working 
standards should be supplied to the factory in form to indi- 
cate the limits within which it is desired to have the work 
made. These practical standards should cover the various 



THE WORKING STANDARDS 263 

matters affecting quality, such as dimension, finish, and 
so forth; and all should be formulated with a reasonable 
mental attitude that makes provision for variations, because 
they are bound to occur. With this clearly understood, we 
are in a position to take up the consideration of the steps 
necessary to secure results in the factory as nearly as may 
be in accordance with the standards of quality desired, it 
being noted in this connection that the above principles 
apply regardless of what the product of the manufactur- 
ing operations may be. Metal work has been used 
merely because it is more inclusive and complete as an 
illustration. 



CHAPTER XVI 
REPETITION MANUFACTURING 

Uniformity for Economy 

The thought of quality as something that is continually 
shifting and varying, when translated into form for use in 
the factory, gives rise, among other things, to the whole 
subject of tolerances and limits. Thus it becomes ap- 
parent that no design is sufficiently complete for intelligent 
manufacturing purposes unless the limits for each and every 
governing characteristic are known. Furthermore, just as 
a clear appreciation of this idea of variations is essential in 
repetitive work, so also is it desirable that the principles of 
repetition manufacturing be understood. 

True manufacturing involves making a quantity of the 
same article, uniform within limits. In this respect it is the 
diametrical opposite of art work. The manufacturer seeks 
to make things alike, but the artist strives for the creation 
of things that are different and individualistic. The first 
system is far less costly; and therein lies the real value of 
manufacturing, because its product is thereby made more 
generally accessible to mankind. We make things alike 
because it is cheaper rather than for the sake of having them 
alike, although many secondary advantages accrue from 
this property of uniformity. In fact, it is so very much 
cheaper to make things alike that the manufacturer can 
afford to incur very heavy expenditures in preparation alone 
— merely for getting ready to manufacture. Because he 
does incur this heavy initial expense, and because all his 
later operations are more or less fixed and governed by these 
preliminary arrangements, it becomes of serious importance 
for him to make them correctly in the first place. 

264 



REPETITION MANUFACTURING 265 

Uniformity of Product Means Uniformity Throughout Production 
In making these preliminary arrangements the manufac- 
turer must not consider the preparatory work in a general 
way as affecting the finished product, but rather in its rela- 
tion to, and effect on, each individual process. This raises 
a point that is frequently lost sight of in repetition manu- 
facturing, namely, the continuous manufacture of one product 
of uniform and standardized quality implies an equal uniform- 
ity and standardization at all stages of its production. Why? 
Because it is cheaper to manufacture in this way, and it is 
cheaper to manufacture in this way because large errors in 
the earlier stages of the work require correction later on, 
when it is not so simple to bring the work into line. Con- 
sequently each component process should be considered as a 
separate production point for the continuous manufacture 
of uniform quality. If one process is left as a loophole for 
large variations to enter, throughout the remaining processes 
a constant struggle must be engaged in to correct them. 
Obviously, this attention to uniform quality must be ex- 
tended to include the raw material itself, clear back to the 
original source of supply. 

It will prove useful in what follows to note incidentally 
that excessive variations in the finished product mean simply 
that there are variations in the earlier processes. For differ- 
ences in the completed articles are the algebraic sum of the 
errors made in all of the earlier manufacturing processes. 
Noting for the moment that interchangeable manu- 
facturing is only one of the several classes of repetition 
work, let us now use it as a specific example in studying 
some of the interesting phenomena of such work. 

Interchangeable Manufacturing 

I have before me an Ingersoll watch of the Reliance 
model, also an Eversharp pencil. Both are products of 



266 THE CONTROL OF QUALITY 

standard quality and must be made by the methods of inter- 
changeable manufacturing. In other words, the attempt 
is made, in manufacturing a quantity of any one of the com- 
ponent parts, to make all of these individual parts so nearly 
alike that any one of them may be used in the assembled 
mechanism with the assurance of subsequent successful 
functioning. Except for the crystal, the springs, and per- 
haps one or two minor parts of the watch, there is no special 
object in having any of the parts interchangeable after the 
mechanism has been sold and placed in use, as there is little 
likelihood of any of them having to be replaced. In fact, 
if all our mechanisms could be proportioned and built as 
perfectly as the "wonderful one-horse chaise," so that all 
the parts would wear evenly and all become worn out at the 
same instant of time, the only value of interchangeability 
of parts in service would be in the rather remote case of an 
accident. Nevertheless, there seems to be a somewhat 
popular misconception that parts are made interchangeable 
for the express purpose of securing the possibility of replac- 
ing parts, whereas the real purpose is to secure certain 
economies in manufacture that are possible only by the 
methods of interchangeable manufacturing. The inter- 
changeability of parts in service, while often convenient and 
frequently important, follows as a by-product quite second- 
ary in value to the primary purpose, which is economical 
production. 

The Industrial Revolution 

Now let us see wherein making parts interchangeable 
decreases manufacturing costs. When Adam Smith wrote 
the "Wealth of Nations" (1776) he described the principle 
of the division of labor by citing the well-known example 
of the manufacture of pins, pointing out that if the work was 
divided up into several operations so that one man concen- 



REPETITION MANUFACTURING 267 

trated on, say, heading pins, and so on for each worker, the 
number of pins produced per man would very greatly exceed 
the production of any one man making complete pins, with- 
out this analysis or dividing up of the work. Thus there 
results a saving or conservation of the experience and skill 
gained in doing the same thing over and over, and we recog- 
nize the outstanding feature of the great change in produc- 
tion which is known as the "industrial revolution" — a 
method that has almost entirely replaced the earlier house- 
hold and handicraft methods of manufacturing. 

The Mechanical Revolution 

The application of labor-saving machinery to produc- 
tion, known as the "mechanical revolution," is closely re- 
lated to the industrial revolution, because as a very early 
result of the division of the labor of manufacture into small 
parts or operations, special labor-saving devices and ma- 
chines were developed. Usually, in order to apply such 
devices effectively, the work obviously must come from one 
operation or mechanical process to the next operation in 
pretty much the same shape and size. Thus the division 
of labor involves making things very nearly alike, and in so 
doing makes it possible to realize economy of effort through 
the greater production secured. Furthermore, the smaller 
subdivision of work permits an unskilled worker to acquire 
quickly the skill necessary to accomplish his part of the 
work. Incidentally, the fact that pieces are more nearly 
alike means that substantially the same thing is done to 
each piece at each stage of its manufacture, in order to ad- 
vance it to the next operation. This must be easier than 
if each piece required special treatment. Incidentally, a 
better quality of work results, and quality tends to become 
more uniform; and from uniformity marked commercial 
advantages accrue. 



268 THE CONTROL OF QUALITY 

Afterward, and when, as an eventual working out of the 
division of labor, certain processes are combined in an auto- 
matic or semiautomatic machine, of course it becomes still 




Figure 61. Height Gage Used with Johansson Blocks 

more necessary to have the work more nearly exact to given 
dimensions and shape. While the division of labor, how- 
ever, leads to making parts alike, the parts do not necessarily 
have to be so much alike on this account alone as to permit 



REPETITION MANUFACTURING 269 

full interchangeability, nor even such partial interchange- 
abilty as will allow assembling by selection of parts that fit 
each other well enough to function properly. 

Economy in Assembling 

The greatest economy, however, in making things suffi- 
ciently alike to be interchangeable comes from the possibility 
not only of the more rapid assembling of component parts 
into the complete mechanism, but also of the use of less 
skilled labor for this work. A workman of very ordinary 
experience and skill can be taught to assemble all, or a por- 
tion, of a complicated mechanism, provided he can use the 
parts just as they are supplied. If, on the other hand, the 
parts must be selected in order to secure an assembly that 
will function properly, much more skill is required; and if 
fitting of parts in the form of doing work on them in the 
assembling room is necessary, then in all probability a very 
high order of mechanical skill and experience is requisite. 
Take the watch for example. Like all mechanisms contain- 
ing a source of power, there is a means of regulating the 
rate of power discharge of the mechanism, within limits. 
While the limits may appear to be narrow, they are great 
enough to take up the differences in action due to the dif- 
ferent combinations resulting from assembling parts which 
have been passed on to the assembling rooms as within the 
allowed variations. Certainly such assembling is not a very 
serious undertaking. But suppose the parts, or some of 
them, required additional treatment in order to fit them 
and adjust them into the mechanism in a way to insure 
proper working. What sort of labor would be required 
then, and how long would it take to complete an assembly? 
Also, would the product be improved by the hand-fitting of 
parts which would be required? 

A small article like a watch is not an extreme illustration 



270 THE CONTROL OF QUALITY 

of this truth, as can be seen very easily by observing the 
strenuous work involved in the regulation of inaccurately 
punched plates in a ship or other steel structure. The work 
required to get the plates into position for bolting-up and 
riveting is greatly in excess of the effort required to punch 
them accurately in the first place; and if the holes are 
enough out of alignment to require reaming to a larger size, 
still more unnecessary labor is expended, extra sizes of rivets 
must be kept on hand, and so on. Furthermore, and most 
important, any such corrective process is not the best 
thing for the structure itself. 

Naturally these same considerations govern in all lines 
of manufacturing. There is a field, no doubt, for hand- 
work in special and distinctive bodies for high-grade motor 
cars, whereas hand-work on the parts of the engine (which 
have been machined already to a high degree of accurate 
conformity to the ideal standard) is not only out of place 
from the standpoint of economy, but actually detrimental 
as well. It is very rarely indeed that anything is improved 
by tinkering. 

The Work of Simeon North and Eli Whitney 

It would be rather interesting to know just when and 
why there arose the present general misconception that 
work is made interchangeable for the simple purpose of re- 
placing parts, inasmuch as the early exponents of the system, 
like Simeon North, Eli Whitney, and their contemporaries, 
certainly understood exactly what the principle of stand- 
ardization really meant. 

"Simeon North — First Official Pistol Maker," a memoir 
by S. N. D. and R. H. North, was published in 1913. It is 
a most interesting contribution to our knowledge of the early 
development of interchangeable manufacturing in America. 
This investigation has made it quite evident that North, for 



REPETITION MANUFACTURING 271 

reasons of economy, lack of skilled men, and similar consider- 
ations, which had nothing to do with interchangeability for 
its own sake, was willing to incur heavy initial expenditures 
and delays in order to achieve an ultimately better result. 
In a letter to the Secretary of the Navy dated November 
7, 1808, he makes this significant comment: 

I find that by confining a workman to one particular limb of the 
pistol until he has made two thousand, I save at least one quarter of 
his labour, to what I should provided I finish d them by small quanti- 
ties ; and the work will be as much better as it is quicker made. 

His contract of April 16, 1813, with the United States, 
for 20,000 pistols, contains the provision: ". . . the 
component parts of pistols, are to correspond so exactly 
that any limb or part of one pistol, may be fitted to any 
other pistol of the twenty-thousand." But a later contract 
for carbines (dated May 2, 1839) added to the requirement 
for uniformity of parts and interchangeability the provision 
that this must be done "without impairing the efficiency 
of the arms" — showing already an evolution in preci- 
sion requirements for better functioning of the complete 
mechanism. 

This early contribution to the economy of manufacture 
is well illustrated by Simeon North's biographers, when they 
quote Daniel Pidgeon's reference 1 to the Connecticut man, 
whose remarkable blending of the engineer and the mechanic 
has done so much for American industry: 

His method of attacking manufacturing problems is one which, 
intelligently handled, must command markets by simultaneously 
improving qualities and cheapening prices. 

Continuous Standardized Production 

In the early part of the present chapter, interchangeable 
manufacture was referred to as one sort of repetition manu- 

1 In "Old World Questions and New World Answers," by Daniel Pidgeon. 



272 THE CONTROL OF QUALITY 

facturing, and was used as an example to illustrate the 
features that are generally applicable in repetition work. 
In explanation of the statement, attention is invited to the 
fact that interchangeable work applies particularly to a 
mechanism built up of standardized parts in such a way as 
to permit disassembling if need be. For even pieces that 
are riveted together may be taken apart. On the other 
hand, the same idea of standardized work applies in all 
kinds of manufacturing. It is, in fact, at the root of suc- 
cess in all production, and for precisely similar reasons. 

The most inclusive definition of modern manufacturing, 
from this aspect, is that it is the continuous production of 
articles whose qualities have been standardized within given 
limits. Since errors in the finished product mean errors all 
along the line of manufacture, it follows as a corollary to 
the general rule that the unfinished articles should be simi- 
larly and at least equally standardized at each stage of their 
manufacture. 

The first need of standardized quality arises at the very 
beginning, with the recovery of raw materials from nature. 
Everything in nature varies, from place to place or from 
season to season, and the variations are large, except in 
unusual cases. It makes no difference whether 1 we speak of 
wheat, cotton, wool, iron ore, lumber, or what-not. It is the 
duty of the basic industries which prepare these materials 
so that they are suitable for use, to reduce the variations as 
much as is reasonably possible. 

Resort must be had first to separation of the raw mate- 
rial into classes or grades. This, in a sense, divides the dif- 
ferences up, and thus reduces them for practical purposes. 
As a second step in the ordinary procedure, two courses are 
open and usually both must be used. Differences due to 
impurities may be removed, and differences in size, shape, 
and so on rectified, and here both chemical and physical 



REPETITION MANUFACTURING 



273 



processes come into play. Any remaining variations from 
lot to lot of the same material may often be rectified and a 
larger body of uniform material produced by using the 
method of mixtures. Finally the need of some sort of 
conditioning process may be indicated, before the material 
is ready for use in the factory. 

Vital Importance of Uniform Quality in Raw Materials 

The importance, in repetition manufacturing, of raw 
material of uniform character and condition cannot be 
overstated. Very often the lack of such uniformity is the 




Figure 62. Set-Up of Johansson Blocks to Check Drill Jig 



18 



274 THE CONTROL OF QUALITY 

root source of the subsequent trouble encountered in trying 
to make a uniform product. What is the value of accurately 
standardized heat treatment, if each lot of steel is different in 
behavior from its predecessor? It is cheaper in the end to 
start with material of uniform character. 

It may seem a far cry from steel to fibers and dyestuffs, 
but the principle just stated holds generally. If textiles are 
manufactured from fibers whose affinity for dyes varies ma- 
terially from lot to lot, and if each lot of dyestuff is of dif- 
ferent hue and strength, the work of producing articles 
uniform as to color-matching is a great deal more difficult 
than if the variations are reduced or removed by careful 
standardizing of the raw materials. 

One often hears complaints in the factory about lack of 
uniformity and standard quality in raw materials, but what 
a pitiful admission of weakness it is to throw the blame on 
the producer of the material. He can hardly be expected 
to know the needs of the consumer, and if the man who uses 
the material will make his exact needs known, he is pretty 
apt to get what he is after. Competition will gradually 
force the producer of material into line, even if he is reluc- 
tant to attempt finer standardization. But to be in a posi- 
tion to call for better materials, the manufacturer must first 
know what qualities he requires and why. Also, once the 
required standards are set, means must be provided for 
measuring the incoming deliveries, for it is useless to set 
standards unless one is prepared to enforce them. 

The factory should be protected by filtering out unsuit- 
able material at the receiving platform of the stockroom. 
This is the first place for the application of control labora- 
tories of various sorts: physical, chemical, metallurgical, or 
perhaps some new kind invented for the needs of particular 
plants. The control of quality begins at this point, in so far 
as the individual factory is concerned. 



REPETITION MANUFACTURING 275 

Continuous Processing 

Perhaps the next logical class of industries, after the 
basic order of raw material preparers, is that large group 
which deals with the assembling of various raw materials by 
methods which involve more or less continuous processing. 
Paper-making and textiles, for example, are highly stand- 
ardized as to their final products, which must be suited in 
each case to meet some definite need of the consumer and to 
render a definite service in relation to price. 

Now, as we have seen already, a uniform product is most 
economically obtained by making all the contributory proc- 
esses equally uniform, as nearly as may be with consistency 
to the requirements of manufacturing economy. Weaving 
a piece of cloth on the loom is a continuous process of assem- 
bling various standardized elements or like parts. It hardly 
can be called interchangeable work, because there is no 
possibility of interchanging parts after the goods are com- 
pleted. Yet the general principle of standardization of the 
process holds — it is advantageous commercially and techni- 
cally to hold the process to a uniform standard within speci- 
fied limits or allowed variations. 

The fact that the errors are worked into the goods might 
seem on first consideration to make a marked difference 
between this type of manufacturing and so-called inter- 
changeable work. In one sense, this is so, but from the 
wider viewpoint, identical principles apply. Thus costs 
would be raised to prohibitive levels if we tried to eliminate 
all broken threads, all missing picks, and all other defects — 
even if we could do so. The only practical way to handle 
the situation is, first, to define what kind of errors and what 
percentage of each kind are to be allowed for a given stand- 
ard of quality, i.e., to set limits; and second, gradually to 
raise these standards in step with the improvement of proc- 
esses, increase in workers' skill, and so on, that will flow 



276 



THE CONTROL OF QUALITY 




Figure 63. Special Milling Fixture Using Johansson Gage Blocks for Locating 

Purposes 



REPETITION MANUFACTURING 277 

from attacking the production problem with quality as our 
basic criterion. 

Duplicate Manufacturing 

There is a large class of manufacturing, known usually 
as "duplicate manufacturing," which is distinguished by 
the use of standards (usually of size, material, and form) for 
the product. Screws, nails, and many other kinds of hard- 
ware are typical. The ordinary uses of many of these 
articles do not require such close limits as the manufacturer 
chooses to follow. It is but another case where economy of 
manufacture, resulting from the division of labor and the 
use of labor-saving machinery, dictates the adoption of the 
methods of standardized repetition work. It is cheaper 
and the product is not only more useful but in every way 
better, because quality yields to control when processes 
are standardized and quality held uniform — within limits. 

Partial Interchangeability 

In the case of assembled mechanisms the various classes 
of repetition work differ among themselves, chiefly in the 
degree of accuracy with which the component parts are 
made. Thus, in passing from work that requires fitting to 
assemble, we find a sort of transitional stage before we reach 
the ultimate form of complete interchangeability. This inter- 
mediate class of work is known as "selective assembling." 
The parts are accurate enough to require no hand-work to 
prepare them for assembling, but are not sufficiently stand- 
ardized to permit using any part in any assembly. Resort 
must be had to selecting parts that go together properly. 

This style of work should never be resorted to except 
when the processes will not permit of the precision neces- 
sary for complete interchangeability, which sometimes oc- 
curs; it is a mistake in this case, just as it is generally wrong 



278 THE CONTROL OF QUALITY 

to assume that loose fits make for easy assembling, except 
when very few parts are mated. A long series of inter- 
related parts requires close work if the assembling is to be 
done without adjustment. Such considerations at once 
require modification of the generally accepted idea that low 
cost and easier manufacture are best obtained through al- 
lowing the greatest freedom in the fit of mating parts with- 
out interfering with proper functioning. 

The advantages of true interchangeability may be ob- 
tained in selective assembling if the selected parts are first 
segregated into classified sizes, thus simulating inter- 
changeability by making groups of parts that assemble 
without selection. ^ 

Production of Machine Tools 

In concluding this chapter it should be noted for com- 
pleteness, that the manufacture of machine tools follows the 
general rule, but occupies a middle position. Economy of 
manufacture requires the use of the methods of interchange- 
able manufacture in the tool-making factory, whenever the 
quantity made warrants its adoption. The great standard- 
ized markets of this country, by providing conditions that 
permitted the use of such methods, are largely responsible 
for our advanced position in machine tool development. 

The fact that the plants which are the users of the ma- 
chine tool maker's product must standardize their proc- 
esses, makes it incumbent on the tool manufacturer to 
provide machines that are highly standardized as to per- 
formance. But machines that give uniform results are 
best made uniform in all their parts, and so the chain of 
uniformity, once started, must remain unbroken. It may 
be observed, moreover, that the quality of machine tools 
should be controlled to a greater nicety than the work those 
machines are to produce. This flows from the fact that 



REPETITION MANUFACTURING 279 

there is an unpreventable slip in accuracy between the work 
and the pattern which the machine follows as a guide in 
generating the work. 

This need for great precision, combined with manu- 
facturing relatively small quantities of machines, has re- 
sulted in a certain amount of hand-work in assembling. 
This work is necessarily done by highly skilled mechanics 
and may furnish an explanation of the scattered character 
of the inspection organization in many machine tool fac- 
tories. The latter situation is especially interesting at 
present in connection with the overhauling of inspection 
methods that has been going on since the war in a number of 
these factories. 

The General Principle 

We have just traced the ideas involved in the continuous 
production to uniform standards of quality. Without any 
attempt toward a strict classification of industries, we have 
analyzed manufacturing sufficiently to show that the posi- 
tive and continuous control of quality to definite standards 
within limits and at all stages of manufacture is at the root 
of production economy. Beginning with the preparation of 
raw materials, it was observed that the same principles held 
good, up to and including the highest type of interchange- 
able work. In the latter case all types are present. Start- 
ing with a uniform material from which are made uniform 
parts, these like finished parts in their turn provide a uni- 
form raw material stock for the assembler, who is thus 
enabled to produce uniform articles to meet some special 
demand of the ultimate consumer. The latter demands 
uniformity because his needs are best met when he receives 
a known performance and a known return in quality for his 
money. 

At each stage of the industrial line the general rule ap- 



280 THE CONTROL OF QUALITY 

plies — the output is greater, the effort is less, the quality is 
higher. Hence it requires less of the consumer's labor to ex- 
change for a higher degree of satisfaction of his needs ; and 
thus the economic situation of everyone is improved. 

But when we generalize that it is best to make things 
uniform, we must remember always that quality varies, 
and that what we really mean is likeness, uniformity, or 
standardization of quality within limits. This, in a word, 
is why quality requires control. 



CHAPTER XVII 
THE DIMENSIONAL CONTROL LABORATORY 

Practical Value of Precision 

The most important advantages of precise dimensional 
accuracy in manufacturing the component parts of an as- 
sembled mechanism are: 

1. The elimination of hand-fitting, with quicker and 

cheaper assembling. 

2. More even wear with consequent greater resistance 

to wear and longer life in service, with correct 
functioning of parts. 

3. Less noise after use, smoothness of action, and 

smaller power losses. "Noise is an automatic 
alarm indicating lost motion and wasted energy. 
Silence is economy. . . . Ml 

With the possible exception of some of the makers of 
very high-grade machine tools, probably no industry has 
advanced precision workmanship to such a high degree of 
perfection as the automotive manufacturers. It is in recog- 
nition of this fact, and with admiration for their achieve- 
ments, that we must turn to them for examples of what our 
methods should be in seeking to bring dimensional quality 
under control. For this reason much of the accompanying 
illustrative matter is taken from automobile factories. The 
lessons are by no means confined in application to that in- 
dustry. 

The basic requirement of precision is that means shall 
be provided for making very exact measurements, and the 

1 From "Creative Chemistry," by Edwin E. Slosson. 

28l 



282 



THE CONTROL OF QUALITY 




THE DIMENSIONAL CONTROL LABORATORY 283 

most sensible way to secure proper surroundings for the use 
of this equipment is to provide a central place suitably de- 
signed for this purpose. 

The Laboratory Proper 

Since uniformity of conditions is the great essential of 
manufacturing, it is even more necessary for a control center 
of quality in manufacturing. Let us now consider some of 
the things which require attention at such a control point, in 
order that influences which are disturbing to the personnel or 
destructive to the equipment may be reduced to a minimum. 

Temperature changes, the greatest cause of variation, due 
to weather changes, can be eliminated by providing artifi- 
cial heat and cold, under uniform control. When this is 
done the temperature is held around 70 F. There remain 
then three other principal causes of disturbance : body heat 
of operators, heat differences of objects brought in from out- 
side, and heat from light rays. The first can be dealt with 
in various ways which are obvious, such as specially insulat- 
ed holding places on instruments. (See Figure 52, page 222.) 
Anything brought in from outside should be allowed to 
stand until temperature equilibrium has been reached. 
When heat from rays of sunlight or from an electric light 
near the work is permitted to affect either work or instru- 
ments, a serious error is likely to occur. For small dimen- 
sions, direct expansion is quite small (for tempered steel it 
is about 0.0007 mcn P er i ncn for one hundred Fahrenheit 
degrees, nevertheless the effect may be specially serious 
when direct expansion is magnified by lever action, e.g., sun- 
light striking the anvils of a snap gage for a few minutes 
would have little effect, but might easily be serious if allowed 
to shine on the handle side, because the effect of the direct 
expansion would be increased and thereby materially change 
the distance between the anvils. 



284 THE CONTROL OF QUALITY 

Humidity and cleanliness are matters requiring consid- 
eration. It would not be extremely difficult or costly to 
make the measuring room dustproof and to supply washed 
dry air in connection with temperature control. The many 
advantages hardly require mention. Such a system would 
seem especially desirable in moist climates, where polished 
steel rusts almost overnight at certain seasons of the year. 
Any system of the sort should have automatic control and 
should be designed to run continuously, as it will not make 
for uniformity if operated only during working hours. 

As regards lighting, daylight illumination should be from 
the north in order to avoid the admission of direct sunlight. 
Greater uniformity and, with certain work, better definition 
will be secured for local illumination if the artificial light is 
taken from "artificial daylight" lamps instead of ordinary 
tungstens. The Trutint lamps made by the Nela Special- 
ties Division of the National Lamp Works (General Electric 
Company) are made in an inexpensive factory-type fixture 
suitable for such work. Care should be taken to place 
artificial lights for local illumination so that their heat will 
not be concentrated in objectionable ways. Good general 
illumination requires white or light neutral gray walls, with 
a dark dado at the bottom. It is always bad to have light 
shining from below the bench level. 

Vibration and noise should be avoided as much as is con- 
sistent with convenient location of the room ; the latter be- 
cause it is a distraction, the former because it is likely to 
interfere with close reading. Accurate work with optical 
projection apparatus which makes use of the optical lever 
for magnifying (for screw threads, shape, etc.), is out of the 
question if vibration is present to any appreciable extent, 
and for such work a separate room may be required, well 
removed from the machine shops. 

Floor covering may be wood, or, better still, battleship 



THE DIMENSIONAL CONTROL LABORATORY 285 

linoleum, which may reduce, if not avoid, the occasional 
accidental error due to dropping things. 

Furnishings should be limited to articles of use in the 
work, but all furnishings should be first class and kept so. 
The laboratory is no place for an old wooden work bench or 
rickety stools. There should be shelf space in cabinets for 
all equipment not in use, and safe cabinets, or preferably 
vaults, for master control standards and models. A con- 
venient wash basin should be provided, unless there is a 
complete toilet room handy. In the checking of accurate 
measurements the tactile sense is no more helped by a coat 
of grease and dirt than it is in mechanical drawing. 

The Surface Plate 

A true plane surface supplies the level foundation upon 
which we build for accuracy. The control laboratory should 
have one large surface plate say, 4 or 5 feet by 8 feet, 
mounted on a firm foundation. Such a plate is of massive 
construction and is not likely to become distorted from 
irregularities of the supporting structure ; nevertheless it is 
certain to change with age and use, even if it is made from 
well-aged metal in the first place. Consequently, it should 
be watched very carefully, and this may develop the need 
for resurfacing at least once in its career. The danger of 
its being affected by temperature changes is slight, if the 
laboratory is kept at nearly standard temperature. 

With careful surfacing when needed, it should be possible 
to keep the surface within 0.00 1 inch of a true plane for the 
greater portion of its area ; yet every surface plate will have 
small hills and valleys whose location should be known and 
allowed for in placing work for measuring. Large accurate 
measurements should be checked by placing the work in 
different positions. In checking the plate to locate these 
irregularities, the first step should be to apply a long and 



286 THE CONTROL OF QUALITY 

accurate straight edge (with reinforced ribbed back) and use 
a feeler gage. The second step should be to sweep the plate 
thoroughly with a surface gage, mounting a sensitive dial 
indicator at the end of the arm, a short arm being first used 
and then a long extended arm. If a further check is desired, 
recourse may be had to the method Whitworth used in 
creating the first standard, namely, by contact application 
of other plates, using Prussian blue between the plates to 
show the humps and hollows revealed by rubbing them to- 
gether. In ordinary shop practice a smaller surface plate 
may be used for this purpose. 

Where much work is to be done, and for other reasons of 
convenience, it is desirable to have one or more smaller sur- 
face and bench plates. It is idle, however, to attempt small 
measurements accurate to teiwthousandths with such equip- 
ment. For such work optically correct plates should be 
used. The crome alloy steel, tool-makers' flats manufac- 
tured by the Pratt and Whitney Company, are about 5 
inches in diameter by Y% inch thick, hardened and heat 
treated by a special stabilizing process. They are finished 
by the Hoke method of lapping (like the Pratt and Whitney 
Hoke precision gages) with surfaces (top and bottom) fin- 
ished flat, well within .000,01 inch and parallel within half 
that error. Precision gages will wring onto them as they 
wring onto each other. 

The Dimensional "Court of Highest Appeal" 

Prior to the invention of the Swedish gage blocks, the 
measuring machine was the only available device for very 
accurate measurements. For some kinds of measuring, 
such as occur in originating or duplicating manufacturing 
standards, an instrument of this type is highly important. 
Some sort of end measure (rod or bar) is often needed to 
check positively an accurate large dimension, and it would 



THE DIMENSIONAL CONTROL LABORATORY 287 

be difficult to conceive of an easier way of insuring accuracy 
than by the use of a measuring machine. 

Resort to such instruments was necessitated by the 
early attempts to obtain real standards of length. In 1742 
beam compasses were used for that purpose in England, 
using both parallel jaws and pointed ends as usual. By the 
use of micrometer screws with graduated heads this instru- 
ment was considered accurate to within 0.000,62 inch for 
comparing yard length standards. At the same time the 
French compared their standards to 0.003 inch, until La 
Condamine, in 1758, said they should be compared to 0.000,- 
89 inch, "if our senses aided by the most perfect instruments 
can attain to that." Fifty years later a lever comparator 
was designed by Lenoir, "which was regarded as trust- 
worthy to 0.000,077 inch." The use of high-powered micro- 
scopes in combination with a carefully graduated scale in 
later measuring instruments has brought this error down to 
0.000,01 inch, although accurate comparison of length 
standards of 3 feet and greater encounter a number of com- 
plications, principally due to molecular forces in the ma- 
terial and to temperature effects. 2 

From these beginnings various types of measuring 
machines have been evolved. There are several European 
models of modern design, while in this country the Brown 
and Sharpe measuring machine (see Figure 65) and the 
Pratt and Whitney machine (see Figure 66) are well known. 

The Brown and Sharpe Measuring Machine 3 

The Brown and Sharpe measuring machine (shown in 
Figure 65) operates on the principle of taking measurements 
by means of a moving scale under a microscope, used in 

2 See Harkness, " The Progress of Science as Exemplified in the Art of Weighing and Measur- 
ing," for these and further details. The way in which these figures are stated is significant of 
the earlier failure to appreciate the principles of the precision of measurement. 

3 From data supplied through the courtesy of Luther D. Burlingame, Industrial Superin- 
tendent of the Brown and Sharpe Manufacturing Company, Providence, R. I. 



THE CONTROL OF QUALITY 




THE DIMENSIONAL CONTROL LABORATORY 289 

conjunction with a micrometer screw and vernier, the entire 
mechanism being supported upon a rigid bed of accurately 
careful construction. Measurements are taken directly 
from the scale and the machine can be set to measure up to 
16 inches. 

The micrometer wheel is graduated to read to 0.000 1 
inch and the vernier plate used in connection with the wheel 
makes it possible to read to 0.000,01 inch. The accuracy 
of the machine, of course, rests fundamentally upon direct 
readings taken from the graduations of the scale, and thus 
depends upon the perfection of the scale and the micrometer 
screw. The sensitivity of the machine may be shown by 
placing the hand on the bed plate between the slides and 
holding it there for approximately 60 seconds, at the end of 
which time the piece will drop from between the measuring 
points. It is interesting to note, however, that the ma- 
chine requires about 20 minutes to return to its normal 
condition after this test. 

The Pratt and Whitney Standard Measuring Machine 4 

The well-known measuring machine made by the Pratt 
and Whitney Company of Hartford, Connecticut (shown in 
Figures 66 and 67) provides not only a scientific instrument 
for use in the laboratory, but, because of simplified and 
standardized methods of manufacture, it is sold at a price 
which permits its wide commercial use and allows any man- 
ufacturer to originate or duplicate his own standards. 

The four principal factors which determine the ac- 
curacy of this machine are the bed, the dividing screw, the 
control of the measuring pressure, and the standard bar 
from which the sliding head is located in known relation- 
ship to the stationary head. 

The bed is of cast iron, seasoned, machined, and lapped 

4 From information furnished through the courtesy of Oscar E. Perrigo, M. E., engineering 
department, Pratt and Whitney Company. 



290 



THE CONTROL OF QUALITY 



straight and parallel for its entire length, and the processes 
through which it passes are of such a nature that the finished 
product is not materially affected by changes of tempera- 



A 


L 




1 







Figure 66. Pratt and Whitney Measuring Machine 

ture or torsional strains which would tend to destroy its 
accuracy. 

'•The dividing screw for the sliding head is cut on a spe- 
cially designed engine lathe which is kept in the laboratory 

where a uniform temperature is maintained at all times. 



THE DIMENSIONAL CONTROL LABORATORY 291 

Compensating devices and adjustment provide a screw of a 
degree of accuracy far beyond that hitherto produced. 

The mechanism for controlling the measuring pressure 
is located in the stationary head. The control is accom- 
plished by means of a sensitive spring arranged so that when 
pressure is applied to the measuring anvil it is communicated 
to another pair of anvils between which a small plug is sus- 
pended by spring tension. When the exact measuring point 
is reached the little plug drops from a horizontal to a vertical 
position indicating that the reading can be taken. By this 
means the human element is eliminated, with the result 
that accurate measurements can be duplicated indefinitely 
without dependence upon the "feel" of the operator. 

The fourth factor is the method of locating the sliding 
head in a known relationship to the stationary head. This 
is accomplished by means of a standard bar located at the 
rear of the machine. Mounted on this bar are a series of 
buttons with highly polished faces upon which are etched 
fine lines exactly 1 inch (or 25 millimeters) apart. The 
graduations on the standard bar are transferred by specially 
designed apparatus from a known bar furnished by the 
Bureau of Standards at Washington, D. C, which, needless 
to say, is accurate to within the narrowest limits permitted 
by human skill. 

In taking measurements the index circle is set to zero and 
the sliding head located to the zero line on the standard bar. 
A microscope (C, Figure 67) equipped with an electric light 
enables the etched line to be seen, the microscope tube being 
adjustable so as to obtain a clear definition. When the 
cross line drawn on the ground glass at the bottom of the 
microscope coincides exactly with the etched line at zero on 
the standard bar K, the tailstock (A, Figure 66) is moved up 
into contact (indicated by the fall of the drop plug) and 
locked in position, where it remains. 



292 



THE CONTROL OF QUALITY 



After the stationary head is located, the sliding head is 
moved back, and then relocated, the compensating zero ad- 
justment F taking care of any variation of position. A 
tangent screw G and lock screw H are provided on the index 
circle for obtaining the last fine adjustment when taking 
measurements. Its multiplied leverage provides a slow 




Figure 67. Details of Measuring Head — Pratt and Whitney Measuring Machine 



THE DIMENSIONAL CONTROL LABORATORY 293 

easy movement of the dividing screw and prevents "going 
by" the measuring point (when the drop plug falls clear out 
of contact). The index circle is also provided with a mag- 
nifying glass E for easier reading of the scale, which is gradu- 
ated to 1/10,000 inch (or 1/500 millimeter). There are 400 
divisions on the English circle and 500 on the metric. One 
turn of the circle is indicated on the linear scale L. 

Vernier. The index circle divisions (.0001 inch, or 1/500 
millimeter) can be subdivided five times by estimation on 
the older machines, but to assist in obtaining very fine ac- 
curate measurements, a vernier is now supplied which will 
subdivide to .000,01 of an inch, or 1/5,000 millimeter. 
Adjustments are provided to take up any wear in the divid- 
ing screw should it ever occur. All anvils are hardened, 
ground, and lapped flat and parallel, and with reasonable 
care the entire machine will give accurate service for years 
with the simplest of adjustments. 

The machines are set and are standard at 62 F. It is 
not necessary to use them at the initial temperature, as 
variations will affect both the work and machine practically 
alike. When used for scientific research, however, the ini- 
tial temperature should be closely adhered to. The ma- 
chines are regularly furnished in 12, 24, 36, 48, and 80 
inch, or 300, 600, 1,000, 1,200, and 2,000 millimeter measur- 
ing lengths. 

Cylindrical supports (B) for holding work to prevent 
springing, are furnished regularly with the machines as 
follows : 

Two with 12-inch or 300 millimeter 
Three " 24 " " 600 
Four " 36 " " 1,000 
Four " 48 " " 1,200 
Six " 80 " "2,000 

The machine regularly requires no special foundation, as 
it has a three-point bearing on the case for equalization. 



294 THE CONTROL OF QUALITY 

The Johansson or Swedish Block Gages 

We now open one of the most interesting pages of 
modern technical achievement — a story of little blocks of 
steel of unbelievable fineness of workmanship. It was in- 
deed fortunate for the development of greater precision 
in machine shop processes that a man of the mental qual- 
ities of C. E. Johansson happened to work in a govern- 
ment arsenal engaged in the manufacture of military small 
arms. 

The technique of this business several years ago required 
something more nearly absolute in accuracy than the 
measuring methods generally in use at that time in machine 
shop work, for it was highly desirable to make military fire- 
arms with the greatest degree of precision that was reason- 
ably obtainable. In order to insure this result, I believe I 
am correct in stating, it was the usual practice to resort to 
positive end measures for all important dimensions, these 
measures being used for checking master or reference gages. 
The consequence was that each government arsenal soon 
accumulated a large quantity of such gage templates, or end 
measures, which constituted their own dimensional stand- 
ards. This will account for the fact that by the use of 
modern finely standardized measurements certain govern- 
ment arsenals have been found to be using an inch which 
varies slightly from the standard inch. It is interesting also 
to note in passing that the use of limit gages is of fairly recent 
adoption for such work. The output was generally small 
(being just enough to keep the arsenal busy in peace time), 
so that an organization of very highly skilled men was de- 
veloped. Owing to their finely cultivated sensitiveness of 
touch, and by taking careful precautions in gage-checking, 
these men were able to produce extremely accurate work, 
using a single fixed dimension on the working gage. All of 
this procedure resulted in the accumulation of a very large 



THE DIMENSIONAL CONTROL LABORATORY 295 

quantity of end measures whose exact values in terms of the 
standard inch were not known with any special precision. 

C. E. Johansson, after three years in the United States, 
during which he acquired both a practical and a theoretical 
education, returned to Sweden and shortly afterward began 
his work as a tool-maker in the Carl Gustavs Stads arms 
factory at Eskilstuna, Sweden ; later he became tool-room 
foreman. He soon came to note that the usual measuring 
equipment differed in its results, which lead him to attempt 
the creation of a system of measuring for such work which 
would give beyond question the accuracy required. Realiz- 
ing the great value of solid blocks of steel, or end measures, 
and guided by the experience gained in the arsenal (which 
adopted the tolerance or limit system in 1889, so that parts 
could be made in quantities and assembled without fitting) 
he proceeded to develop the famous Swedish or Johansson 
block gages, which in 1906 he announced to the mechanical 
industries at large. 

Much more recently a factory has been established at 
Poughkeepsie, New York, for the manufacture of the 
Johansson standards in this country, where they find a 
wide application in industry. 

These blocks possess the following interesting character- 
istics : 

1 . They are made of steel which has been heat treated 
and seasoned to practically eliminate warping or "growing." 

2. The surfaces are flat and parallel to within .000,01 
inch or less. 

3. These parallel surfaces are distant from each other to 
within .000,01 inch or less of the absolute dimensions stated 
on the block. 

4. These accurate surfaces permit of wringing the blocks 
together, and they are arranged as to dimension so that by 
suitable combinations of the blocks, as indicated in the va- 



296 THE CONTROL OF QUALITY 

rious illustrations, practically any dimension desired may 
be obtained without appreciable error. 

When packed together in this manner, not only is the 
variation per inch kept as low as .000,01 inch or less, but the 
surfaces are in such perfect contact that they adhere to each 
other (probably because of surface tension of the minute 
film of oil between them) with a force far in excess of mere 
atmospheric pressure. It is almost certain to result in 
"freezing," if the blocks are left in contact for several hours. 

As will be observed from the various illustrations, posi- 
tive end measures of this sort find wide and useful applica- 
tion in any tool work that requires accurate determination 
of dimension. No matter how many sets are used in the 
factory — and it is an economy to use several — each dimen- 
sional control laboratory should be equipped with one set of 
such blocks to be retained solely as a final check for dimen- 
sional control purposes. If the blocks are given proper care, 
they should remain practically unchanged from year to year. 
Ordinary inaccuracies due to wear, accident, or abuse, may 
be discovered quite readily by checking them against each 
other in different combinations. The result is a court of 
last appeal for dimension in the fool-proof form of flat steel 
blocks, or end measures, in fixed sizes. 

As an example of continued precision of the block, it may 
be noted that a set (No. 3353) purchased in October, 191 8, 
was returned to the Johansson Company in October of 1920 
for rechecking. This set bore an engraved copper plate on 
the box stating that it was to be used only for checking other 
Johansson standard blocks and could be used only upon 
requisition by certain specified officials of the owning com- 
pany, which happened to be the Ford Motor Company. 
This reference set, of course, had received excellent attention 
and very slight use. Inspection by the Johansson Company 
at Poughkeepsie showed that two blocks had worn approxi- 



THE DIMENSIONAL CONTROL LABORATORY 297 

mately .000,01 inch below normal size. All the rest of the 
blocks, including the 2,3, and 4 inch blocks, showed varia- 
tions from normal size of less than .000,01 inch and most of 
them less than .000,005 inch. 5 

The Johansson methods of manufacture and measure- 
ment have been kept a business secret, although Mr. Johans- 




Figure 68. Special Set of Johansson Block Gages 

Accurate to within one-millionth of an inch. 

son has disclaimed the use of the interferometer or light 
wave method of measuring, which has caused a good deal of 
speculation on the part of mechanical engineers and tool- 
makers as to just what method of measurement he uses. 
Despite the absence of information on this subject, we 
must nevertheless admire so remarkable an achievement. 
In fact, one can form a fairly good idea of how much 
mechanical sense anyone has by observing his attitude 

6 From information furnished by Huber B. Lewis, Vice-President, C E. Johansson, Inc., 
Poughkeepsie, N. Y. 



298 THE CONTROL OF QUALITY 

toward the Swedish block gage itself. As an example of 
what can be done, attention is invited to the set shown in 
Figure 68, which was made by Mr. Johansson in order to 
provide a set of blocks accurate within the one-millionth 
part of an inch. 

The Pratt and Whitney Precision Gages 

During the war the need for precision end measures of 
the Swedish type was greatly increased, and it is much to the 
credit of the United States Bureau of Standards that it 
became possible to develop very precise gage blocks through 
the Hoke method of lapping and the use of the interference 
of light waves for measuring. William E. Hoke of St. Louis 
began this development with the Bureau of Standards, and 
later as a major in the Ordnance Department was enabled 
to make further progress. Gage blocks are now made by 
several concerns in the United States. An interesting de- 
scription of how the Hoke type of gages are made by the 
Pratt and Whitney Company may be found in the April, 
1920, issue of Machinery. The method of measuring by the 
utilization of light waves is described in the May 22, 191 9, 
issue of the Iron Age. 

Comparators 

It will be noted from a number of the illustrations of 
gage blocks in use that the blocks are being applied with the 
assistance of an instrument for accurately comparing meas- 
urements. Figure 69, for example, shows the blocks being 
used with an American amplifying gage, as made by the 
American Gage Company of Dayton, Ohio. The American 
amplifier operates on the lever principle re-enforced by a 
dial indicator, as shown in the illustration. Figure 38 
shows a similar application, using the Prestometer or Prest- 
wich fluid gage, as supplied by the Coats Machine Tool Com- 



THE DIMENSIONAL CONTROL LABORATORY 299 




Figure 69. American Amplifying Gage Used with Swedish Gage Blocks 



300 THE CONTROL OF QUALITY 

pany, Inc., of New York. The Prestwich fluid gage largely 
eliminates the sense of touch and measures differences of 
dimension with extreme accuracy through the use of fluids 
and capillary tubes in connection with metal diaphragms 
and a micrometer scale. If this instrument is used with 
care in the selection of suitable sized tubes for the work in 
hand, and if the adjustments are made with reasonable atten- 
tion to the elimination of air bubbles, setting to zero, etc., 
it is an invaluable auxiliary device for use with gage blocks. 
While it is true that fairly accurate comparisons may 
be made by using the holders or straight edges provided 
with the gage block sets, very precise comparisons are much 
simplified by using an instrument of the comparator type, 
in which differences in reading are magnified by some form 
of mechanical or fluid lever and the reading scales of which 
can be set to zero for each dimension. 

Miscellaneous Equipment 

Various well-known miscellaneous auxiliary equipment 
for measuring are listed in detail in most small tool cata- 
logues, and these should be found in every dimensional 
control laboratory. New devices of considerable usefulness 
are continually coming to the front, however, such as the 
following : 

i. Optical projection apparatus for comparing screw 
threads and profiles is valuable for several purposes, as re- 
ferred to in Chapter XIX on the gaging of screw threads. It 
should be noted that such apparatus requires freedom from 
vibration. 

2. The Johansson set of precision angle blocks. Thisisa 
very useful outfit for precisely checking angles and should 
find much wider application. 

3. While not directly connected with dimension, various 
control instruments for measuring hardness, such as the 



THE DIMENSIONAL CONTROL LABORATORY 301 

Brinell tester and the Shore scleroscope, should form part of 
the laboratory equipment. The Bureau of Standards 
Technologic Paper No. 1 1 gives a "comparison of five meth- 
ods used to measure hardness." 

Personnel 

Thus far only the material equipment of an ideal dimen- 
sional control center has been discussed. Needless to say, 
the selection of the personnel of such a control center is also 
extremely important. Probably everyone inexperienced in 
the use of measuring apparatus starts out with the idea that 
manual dexterity and tactile sense is associated only with 
the slender tapering fingers of the so-called artistic hand. 
But any such notion is quickly dispelled by observing the 
accurate work turned out by men with fat pudgy fingers. 
The only proper and scientific test of measuring ability is 
actual trial. There is no reason why candidates for jobs of 
this kind should not be tried out by actual measurement of 
their work, which will soon reveal, if the test is scientifically 
conducted, any lack of tactile sense, accurate eyesight, or 
skilfulness in making fine adjustments. 

One of the first requisites for the proper use of scientific 
apparatus is cleanliness. The laboratory itself should be 
kept immaculately clean and clear of everything except what 
is needed for the work in hand. The same comment applies 
to the personnel, who should be encouraged, by the provi- 
sion of facilities for washing, to keep their hands clean. In 
hot weather this may be especially important, because 
there are some people whose perspiration quickly rusts and 
soon destroys highly polished steel surfaces. "The Atlas 
Ball Company of Philadelphia tests the hands of applicants 
for the positions of inspectors, with a view to detecting acid 
perspiration. The hands of many people affect a fine steel 
surface seriously. In some cases breathing on steel dis- 



302 THE CONTROL OF QUALITY 

colors the surface. The Atlas Company also tests for 
this." 6 

Assuming that the people engaged are well suited to the 
work in hand, it is highly important to impress upon them 
the wide influence of the control work they are performing. 
In any work of the sort special attention should be paid to a 
standard technique for making various measurements. 
Many errors which cause lack of uniformity may be elimi- 
nated if certain measurements are always made in the same 
manner. It hardly need be added that a part of this warn- 
ing applies equally well to the high cost of hurrying. Swift- 
ness is one thing, and a very desirable thing, but hurrying has 
no place in work of the sort, where one blunder will be almost 
indefinitely repeated when the tools or gages get out into 
the shop. 

6 The Johansson Journal, Vol. I, No. i. 



CHAPTER XVIII 
GAGES AND GAGE-CHECKING 

When Should Fixed-Dimension Gages Be Used? 

Various types of gages have been developed for special 
purposes, and in approaching any manufacturing problem 
where the question of dimension is important it must first be 
decided whether any special operation should be controlled 
through the use of flexible measuring instruments, such as 
micrometer calipers, or some special form of gage in which 
the dimension is physically worked into the gage, usually in 
permanent form. In each instance special consideration 
should be given to such questions as : 

Which type will give the best results from a mechani- 
cal standpoint? 

Which is best suited to use by the available labor? 

Which is the more economical, both as to first cost and 
in use? 

Flexible measuring instruments such as micrometer 
calipers require greater skill in their application and are 
more subject to personal errors due to inaccurate reading of 
the scale, incorrect remembrance of the dimension, and dif- 
ferences in "feel." Ordinarily it takes more time to apply 
the measuring instrument than it does to use limit gages 
with fixed dimensions. This does not always hold true, 
however, because there are many expert mechanics who 
take very rapid and accurate measurements with microm- 
eter calipers. It must be remembered also that such 
measuring instruments are capable of application to several 
different jobs and, consequently, should be used where the 

303 



304 THE CONTROL OF QUALITY 

quantity of work prohibits the making of special gages, 
although the recently developed commercial types of adjust- 
able limit gages obviate this difficulty of expense for many 
applications. 

No gage, and especially no measuring instrument, should 
be applied to work in motion. To prevent this requires a 
certain amount of supervision and education of the operator. 
It is by no means uncommon to see a skilled workman apply- 
ing a micrometer caliper to work on a grinding machine or a 
lathe with the spindle still in motion. Frequently, too, the 
proper way of holding and applying micrometer calipers is 
not appreciated. Through the courtesy of the Brown and 
Sharpe Manufacturing Company a number of photographs 
have been secured showing the proper way of holding and 
using micrometers of various types. (Figures 4, 5, 51, and 
60.) 

Fixed-Dimension Limit Gages 

Fixed-dimension gages without limits are practically a 
thing of the past. They depend entirely upon the feel of 
the operator and have nothing to commend them, for even 
their expense of manufacture is little increased by making 
a double opening, to the limit sizes of the tolerance. 

There would seem to be little doubt that fixed-dimen- 
sion limit gages are mechanically suitable for all work that 
ordinary micrometers will handle. From the standpoint of 
first cost their application depends upon the quantity or 
work to be done, but since their use requires less skill and 
greatly reduces the chance of error, it is probable that their 
use will be widely extended. 

Frank 0. Wells in an article ] calling attention to the 
probability that the widespread use of gages will be a dis- 



x "Future of Gages in Manufacturing," published in the March, 1920, issue of Industrial 
Management. 



GAGES AND GAGE-CHECKING 



305 




306 THE CONTROL OF QUALITY 

tinguishing feature in American industry, makes the point 
that "gages allow departments which cannot see each other, 
which are separated by walls or courts or other departments, 
to act in exact coordination." The following quotation 
from his paper is of special interest: 

A workshop establishing a definite tolerance system, in almost 
every instance, unless the shop is in serious condition, will find that 
the desired tolerance will be greater than has been taken advantage 
of in the great majority of pieces made before a definite tolerance 
was set. The installation of limit gages will merely find and throw 
out the small minority of pieces which have wandered from the 
standard the mechanics themselves set up, but have no definite 
means of adhering to. It is the exceptions to the rule which cause 
the most bother. The gage cuts out the exceptions. 

In the automobile industry, which has brought dimen- 
sional control to such a fine point, the use of fixed-dimen- 
sion limit gages has been widely extended. In the Packard 
Motor Car Company's factory, for example, over 40,000 
gages are in use. Throughout all divisions of the factory 
limit gages are used extensively and are set with tolerances 
ranging from plus and minus 0.0005 i ncn to plus and minus 
0.010 inch. On tolerances less than plus and minus 0.0005 
inch better results are obtained by using an amplifying gage 
or a fluid gage, as described later. 

In gage design both economy and technical requirements 
point to the advisability of using simple single-purpose gages. 
The use of flat plate gages, on which several openings are 
shown, has little to recommend it, for almost always some 
one of the dimensions will show greater wear than the others, 
so that if the gage is to be saved for future use this opening 
must be peened. The appearance of the gage is thus de- 
stroyed, and, as everyone knows, no battered -up gage ever 
receives the same respect from the user, as one in perfect 
condition. 



GAGES AND GAGE-CHECKING 



307 



Adjustable Limit Gages 

There are several types of adjustable limit gages on the 
market which permit the economical extension of what are 
practically fixed-dimension limit gages. (See Figures 52 
and 54, showing the general features of the Johansson adjust- 




Figure 71. Adjustable Limit Snap Gages — Pratt and Whitney Type 



able limit gages, both snap and plug; also Figures 71 and 
72, showing similar information for the Pratt and Whitney 
gages.) 

The wide anvil gage is coming into greater use and has 
very much to recommend it, not only because of decreased 
wear but because the greater bearing surfaces tend toward 
more accurate results. Attention is invited to a similar 
economy in the use of plug gages with reversible ends which 



3 o8 



THE CONTROL OF QUALITY 




Figure 72. Adjustable Limit Plug Gages with Reversible Ends — Pratt and 

Whitney Type 



GAGES AND GAGE-CHECKING 309 

permit a longer useful life. (See Figure 72.) The fact that 
ends are removable is advantageous, as the "no-go" end 
always wears less than the other. 

Multiplying Gages 

It is an interesting fact that in the application of close 
limit gages there may be a difference of as much as 20 per 
cent or more in the number of pieces passed by the inspector, 
depending upon his mental attitude and material surround- 
ings. Very slight actual differences may thus become very 
great quantitatively. A purchaser's inspector may differ 
very decidedly from the factory inspector in the use of the 
same gage. This fact alone accounts for the increasing use 
of gages in which such small differences are enhanced or 
magnified to a point where measurement becomes imper- 
sonal. Where the work warrants the expense, the use of 
such gages is almost always desirable for better work, and 
especially so when it is necessary to use less skilful help and 
to obtain a greater assuredness of results with such help. 
The Packard practice, for example, has developed that for 
tolerances less than plus and minus 0.0005 inch much greater 
certainty is obtained by using an amplifying gage or the 
Prestwich fluid gage. Figure 38 shows a photograph of an 
operator using a Prestwich fluid gage on piston pins, the 
size of which is held to plus zero and minus 0.000,25 inch. 
These gages are set from a " master " and are checked against 
the "master" after every 100 pieces. The gages are used 
in both production and inspection on such work, and at 
times it has been found that, if the work is held to a closer 
limit than plus or minus 0.0005 inch, the operator will hug 
the high limit for fear of getting the pieces undersize. With 
fixed gages on work of this kind, the points or anvils will 
wear quite rapidly and as a result crib inspection would 
show about 25 per cent of the pieces oversize. 



3IO THE CONTROL OF QUALITY 

The principal types of multiplying gages are as follows : 
i . The multiplying lever type. With this type of gage 
it is important to avoid backlash or slip by keeping the 
chain of levers under pressure from one direction in order 
that the spring or other tension device may quickly restore 
the parts to the zero measuring position. The points of 
juncture in the link work are important. Flexible tape 
connectors or conical pointed ends in conical hollows are 
desirable for great accuracy, but wear must be provided 
against with care. All gages of this type should have posi- 
tive adjustment for the zero point and should be provided 
with standard test pieces. 

2. Dial indicators may be used to accomplish the same 
purpose of multiplying errors (see Figure 36), and so may 
the micrometer heads which are commercially obtainable. 

3. The amplifying gage (Figure 69), and the fluid gage 
(Figure 38), which are primarily multiplying comparators. 
These also are suitable for use in this connection, as has 
been stated heretofore. 

4. Flush pin gages. These are made to utilize the tactile 
sense for the detection of small differences, as the finger-tip 
is very sensitive and is able to feel very small errors. Their 
use should be restricted, however, to work on which other 
less complicated devices are unsuited. 

Special Gages 

Special situations may be handled by various designs of 
gages and measuring instruments, in which there is room for 
the greatest ingenuity and resourcefulness of the gage de- 
signer. These include such devices as special testing fix- 
tures, (e.g., as used for measuring cam-shafts, etc.); con- 
tour, profile, or outline gages, and so on. 

It is often useful, in drop forge work, to provide hot 
gages for checking forgings more promptly. In such gages 



GAGES AND GAGE-CHECKING 311 

allowance is made for expansion of the work while hot. 
Another method is to keep the gage hot and to fit an insu- 
lated handle to it. 

Modern methods of thread-gaging have developed a 
great many special devices, including the use of the optical 
lever in projection apparatus. A number of these special 
devices are treated in detail in Chapter XIX. 

Gage Tolerances 

The economical use of gages requires that even greater 
care be given to setting the tolerances on the dimensions of 
the gages themselves, than for the work. Speaking mathe- 
matically, this process is like the second differential, in 
which the tolerance for the work is the first differential. 
With adjustable gages the matter of wear is easily disposed 
of, but there are many instances in which the task is not so 
simple. As a general guide the rule is sometimes followed 
of allowing a gage tolerance equal to 10 per cent of the tol- 
erance for the work proper. It is good practice to make 
limit plug gages 0.0002 inch full on the "go" end to allow 
for wear, since the "go" end of any gage wears much more 
rapidly than the " no-go " end. Copper plating is sometimes 
resorted to, in order to build up the wearing surface for gage 
anvils. It is good practice in many instances to have a 
systematic plan for replacing worn working gages with worn 
inspection gages. 

The Application of Gages 

Investigation will reveal that there is a great field for 
educating workers in the use of gages. Special attention 
should be given to gage instruction cards (see Figure 49, 
showing a portion of one such card as used in the Lin- 
coln Motor Company's factory) . The technique necessary 
for accurate application of gages demands separate study 



312 THE CONTROL OF QUALITY 

and there is undoubtedly great room for development of 
motion study in this work. More gages should be mounted 
upon flexible stands which will permit the gage to adjust 
itself readily to the work as well as allow the operator to use 
both hands. 

Gage-Checking 

The use of limit gages brings with it a special problem of 
co-ordination. In a large factory using thousands of gages 
there is every need for the intensive and practical applica- 
tion of systematic methods in gage-checking. Troublesome 
gages and gages subjected to hard usage should be checked 
very frequently indeed. As a general rule gages with limits 
of plus or minus one-quarter thousandth should be checked 
at least twice a week, those with limits of plus or minus one- 
half thousandth at least once a week, and those with limits 
of over one-thousandth, at least once a month. In addi- 
tion, to provide against accidental errors, all of the devices 
for catching such errors should be utilized. These have 
been listed in detail in Chapter IV, pages 60 and 61. 

Naturally a problem of this sort requires that the individ- 
ual gages be numbered, that there be a card catalogue sys- 
tem and a tickler file, and, more important still, that some 
responsible individual be charged with the duty of following 
up this work. This control of dimension of course proceeds 
from the dimensional control laboratory referred to in the 
preceding chapter. The work will be more easily controlled 
if handled entirely through the inspection department and 
if all working gages are issued from inspection centers 
throughout the plant, whether they be central inspection 
groups or merely the offices of department inspectors. 

As noted before, the fact that gages wear makes it 
necessary to provide a chain of checking devices reaching 
from the working gage (which is subject to the most wear) 



GAGES AND GAGE-CHECKING 313 

back to some master gage template or standard measuring 
machine which is subject to extremely little wear and, there- 
fore, reasonably sure of remaining constant. The number of 
links in this chain is frequently dependent upon the number 
of times the working gages are to be applied and upon their 
relative wear. Thus, for a very close dimension, a soft steel 
or even a hard steel template might be applied by an expert 
in 1,000 checkings without serious wear. Then in such a 
case, if the quantity of work contemplated more than 1 ,000 
checkings or applications of the template, we should have 
to construct one more link in the chain in order to have 
something to check the template. 

In building up this chain for dimensional control several 
terms have been employed, but there is no set of definitions 
in general use. The definitions recommended in the Prog- 
ress Report of the Committee on Limits and Tolerances in 
Screw Thread Fits, as published in Mechanical Engineering, 
August, 191 8, are: 

Master Gage. A gage which is kept as a standard solely for com- 
paring reference gages. 

Reference Gage. A gage used by the manufacturer and by which 
the workman's gage is tested. A copy of the master gage. 

Standard Gage. The English term for Master Gage. 

Shop or Workman ' s Gage. A gage used by the workman in 
everyday practice. It is tested by or with the Reference Gage. 

The above definitions are a sufficient guide for ordinary 
purposes, but many gages will be checked with greater ease 
if they are provided with close-fitting templates as an addi- 
tional step in the chain. Further, for straight dimensional 
work (that is, excluding special shapes, such as screw threads 
and profiles) several of the early steps in the chain of control 
gages may be eliminated by the use of Swedish gage blocks. 
The basic principle, however, must be observed with care: 
One master set of blocks should be retained solely for checking 



3H THE CONTROL OF QUALITY 

the other sets of blocks which are used in the direct dimensional 
checking of gages and tools. 

The Slip in Transferring Size 

Another chain of error arises in the possibility of slip in 
passing from dimension to dimension. With the feeling 
that the Johansson Company's experience in the matter of 
making fine adjustments would be of interest in this respect, 
they were asked for their opinion on the matter. The follow- 
ing information was furnished by C. E. Johansson, Inc. 
through the courtesy of Huber B. Lewis, Vice-President: 

It is possible to transfer size without any observable slip. We 
do it regularly in our laboratory work. Our checking instruments 
are, of course, of extreme delicacy and we are dealing, in most cases 
with surfaces of extremely accurate finish. It seems to us that the 
amount of slip which might occur in the practical application of 
measuring implements depends, first upon the sensitiveness and the 
uniform accuracy of the comparator, and second upon the finish 
of the surfaces being compared. As an illustration: if a 
comparator were set by using a standard plug with a fine lapped sur- 
face, a ground part checked on this comparator would probably 
register large because of the surface irregularities. A clearer com- 
parison might be the slip between the plug templet and a ring made 
to fit this templet. In practical tests we have made on plugs and 
rings i "in diameter, we find that a clearance of approximately .0001" 
should be allowed in order for the plug to enter the ring with a nice 
wringing fit. Actual measurement would, therefore, show the ring 
to be .0001" larger than the plug to which it was fitted which would 
probably establish for practical purposes, a slip in measurement of 
.0001". By using extreme care in the finish of the surfaces of the 
plug and ring, paying particular attention to roundness, this slip 
can be reduced to .00005" an d the plug inserted in the ring without 
using force. On the other hand, a clearance of more than .0001" 
would be required if the plug or ring were not round and smooth. 

Two Johansson Standard Gage Blocks can be checked against 
each other where the slip would not exceed .00001". Take two new 
1" blocks which are exactly alike within .00001" or better, wr ng end- 
radius jaws on one block; the other block can be inserted in the recess 



GAGES AND GAGE-CHECKING 



315 



between the extension jaws so that it will remain in place when sus- 
pended, through the niceness of fit. It may be said that some slip 
occurs in the union between the first block and the end pieces due to 
the filament of oil or moisture between the surfaces; whatever that 
slip may be, if at all appreciable, will also exist between the jaws and 
the second block when it is inserted between the extension pieces. 
This would also be true in rougher work, for instance, a snap gage 
set to a templet. Assuming that some slip occurs in mating the 
snap gage to the templet, a corresponding slip would occur between 




Figure 73. Pratt^and Whitney Taper Gages 



the snap gage and the parts checked by it so that the parts would 
correspond very closely with the original templet. 

Mr. Johansson illustrates this principle of fit in a very interest- 
ing way. He takes ai" Standard Gage Block with the radius jaws 
extending down each side and stands the block on the table before 
him. By the side of the block he stands a 1" plug gage, finished to 
the same degree of accuracy as the standard block. After making- 
sure that both pieces are of the same temperature, he inserts the 1" 
plug gage into the snap gage opening formed by the l" block and the 
end pieces. You will note that the surfaces of the plug gage and the 
extension pieces are in contact only along a hair line on each side. 
Notwithstanding the slightness of this contact, the fit is sufficiently 
nice to permit Mr. Johansson to raise the entire combination by 
lifting the end of the plug gage. 



316 THE CONTROL OF QUALITY 

Mr. Johansson then takes the standard block combination and 
holds it in his hand while he counts five slowly. The plug gage is 
again inserted and this time it is impossible to lift the standard block 
combination with the plug due to the expansion of the block. The 
plug is then held in the hand while he again counts five, thus bring- 
ing the plug approximately to the same temperature as the block 
again and this time the fit is the same as it originally was and it is 
possible to lift the standard block combination by lifting the end of 
the plug. The amount of expansion would, of course, depend upon 
the difference between the body temperature and the temperature 
in the room where the experiment is performed, but the change 
would not account for more than two or three hundred thousandths 
of an inch, perhaps, and this again illustrates the very small amount 
of slip that may occur when surfaces of equal finish are compared. 

After every precaution has been taken to see that the 
proper gages, correctly checked from time to time and kept 
to dimension, are provided, and even if they are properly 
used, there still remains much to be done if precise work is 
to be secured with certainty. For this reason in Chapter 
XX will be found some comments on the points to be ob- 
served in precision processes, as well as data indicating 
the present state of the machining art in the matter of 
dimensional accuracy. 

Chapter XIX is devoted to the presentation of the very 
special and intricate business of screw thread production 
and gaging. Many of the devices and methods, however, 
are more generally applicable to irregular outlines, contours, 
and forms. 






CHAPTER XIX 
THREAD-GAGING 1 

Evolution of Thread-Gaging 

The evolution of thread-gaging is an epitomized history 
of all gage development, beginning with simple ring and 
plug gages and micrometer calipers and then running the 
gamut through a long series of specialized measuring and 
checking devices up to the use of the latest methods of opti- 
cal projection. This array of equipment and the great and 
continued effort of many expert engineers involved in its 
creation, is warranted by the value of the screw thread as 
an element of mechanism and is made necessary by the diffi- 
culties inherent in accurate thread-making. 

The beneficial influence of munition and automotive 
requirements are clearly traceable in this evolution. More 
perfect interchangeability without sacrifice of dependa- 
bility or strength in relation to weight have operated to en- 
hance the importance of precision in the manufacture of 
threaded parts. In fact these characteristics have been 
greatly improved, with corresponding improvement in the 
apparatus for controlling their quality in manufacturing. 

So great a variety of gaging devices is now available as a 
result of the recent intensive development just mentioned, 
that the first practical problem encountered in building up 
a control system for threaded work is the selection of appa- 
ratus sufficiently positive in effectiveness without being too 
cumbersome or complicated. It is very easy indeed to build 
up a long chain of control from the working gage through 

1 The author is indebted to the Honorable James Hartness, Governor of the State of Ver- 
mont (and formerly President of the Jones and Lamson Machine Company of Springfield, Vt.) 
for his kindness in furnishing much of the material presented in this chapter. 

317 



3 1 8. THE CONTROL OF QUALITY 

inspection, reference, and master gages with their check 
templates, up to final master models. But the ramifica- 
tions thus introduced are all potential sources of error and 
necessitate solicitous watching. 

Anything that can be done without sacrificing efficiency 
to reduce this complexity by shortening the chain between 
the work itself and the final control equipment is highly de- 
sirable for many and very apparent reasons. It has been 
shown already how the chain may be shortened in simple or 
single dimensional work by the use of Johansson block 
gages. It is now proposed to show how the same thing 
results in precise thread control from the use of modern 
optical projection apparatus. 

Again quoting L. P. Alford's frequent statement, "The 
purpose of industry is to make goods," thread-gaging devices 
are of no value for their own sake, but merely as a means for 
assuring the production of threaded parts in accordance 
with the desired standards. The more direct and simple 
such devices can be made the better, but the first step, as 
always in the control of quality, is to study the product, the 
errors which enter into its production, the causes of these 
errors, and the means of regulating the manufacturing proc- 
esses where errors are made. 

In the analysis of screw-thread elements essential to 
strength and dependability, James Hartness states: 2 

On account of the vagueness of our general knowledge of the 
conditions under which it takes its stress, we frequently underesti- 
mate the importance of the screw, and, through ignorance, continue 
practices that greatly increase the hazard of life in travel by rail, 
automobile or airplane, as well as lessen the reliability of perform- 
ance of other pieces of machinery. A screw-thread fastening is very 
dependable if the two component parts are properly fitted. 

While it is not possible to attain perfection in this work, an 
analysis of the various elements that are essential for strength and 



2 "Optical Projection for Screw-Thread Inspection" in Mechanical Engineering, Feb. 1919. 



THREAD-GAGING 319 

dependability, and the reduction of weight, will greatly simplify our 
efforts and make it possible to attain a point much nearer per- 
fection. 

Briefly stated, a screw's reliability depends upon the following 
elements: 

A Material 

B Form of profile of the thread 

C Diameter of the screw 

D Lead or number of threads per inch. 

After the foregoing general characteristics have been deter- 
mined, we must consider the following details which depend on the 
methods and skill employed in production: 

1 Smoothness and density of surface 

2 Fit, which relates particularly to the exact relationship of 

the size of the two component parts 

3 Precision of lead, which relates to the precision of advance 

of the helix or degree of precision with which the 
number of threads per inch are made 

4 Uniformity or steadiness of advance of helix 

5 Form, relating to contour of a single thr ad 

6 Roundness, as relating to the circular path of the helix 

7 Parallelism or taper. 

These elements are all inter-related. 

Inter-relation of Thread Elements 

The last sentence is particularly significant. Before 
threading, the problems of ordinary cylindrical or tapered 
work are encountered, such as maintaining diameters, round- 
ness or concentricity, and parallelism. These difficulties 
are carried over into the threading, where they are accentu- 
ated by the creation of spiral-warped surfaces which add the 
complications of pitch or lead of the screw, the angular 
form of the thread, and several diameters instead of one. 
Thus errors accumulate in three dimensions. In the case 
of a single screw thread considered alone the inter-relation 
of errors must be carefully taken into account ; for example, 



320 



THE CONTROL OF QUALITY 







Figure 74. An Exaggerated Form of Stud 

To illustrate the fact that when there is a difference in lead between the screw and 
the nut or threaded hole the middle threads do not touch either in the gage or the 
work until the opposing end threads are crushed. It also illustrates the conflict 
between the stresses at the two ends of the engagement. Courtesy Jones and Lamson 
Machine Company. 



THREAD-GAGING 32 1 

a variation in pitch may involve a much greater error in 
effective diameter. 

When the investigation of inter-related errors in screw 
threads is extended to include mating parts, as it ultimately 
has to be in every case, the percentage feature of precision 
is involved because the error in the lead of the thread varies 
with the length of the thread. The possibilities in the latter 
case are well illustrated in Figure 74. 

The preceding general discussion of the elements of 
threads and their accompanying errors assumes theoreti- 
cally smooth surfaces. In practice, however, the surfaces 
of threads are not smooth, nor are edges continuous lines 
and true curves. The manufacturing processes inevitably 
leave their marks in the form of irregularities, chips, and so 
on, which vary in magnitude with the character of the work. 
No matter how slight these irregularities, their effect, singly 
or collectively, is to increase errors of gaging or measuring. 

It is not the purpose of this book to go into the techni- 
calities of the various features of design, and it is assumed, 
therefore, that the design provides for safe clearances be- 
tween mating parts, especially bottom and outside clear- 
ances. It is assumed also that the design provides for 
normal wear of cutting tools, especially at the points and 
edges where wear may ordinarily be expected to reach its 
maximum effects. With these assumptions, then, we are 
chiefly concerned with the remaining factors of lead, pitch- 
diameter, and slope or angle. The first two usually require, 
and in fact warrant, the most attention. Their inter-rela- 
tion is such that lead, especially in long screws, is of para- 
mount importance. 

Working Thread Gages 

The usual gages for inspecting threaded parts in the shop 
are of the well-known plug and ring type (see Figures 75 and 



322 



THE CONTROL OF QUALITY 



76). A series of similar gages can be made for gaging the 
various elements of the thread separately, but it would 
hardly be wise or worth while to furnish such a series as 
working gages or even as inspection gages for use in the 
shops. Consequently the use of several gages for such work 
finds little application outside of the tool-room in thread- 
chasing. The gaging system for practical shop use, there- 
fore, reduces to limit threaded plug and ring gages which 
gage all essential elements at once. , This involves for the 
threaded hole: 

(a) Threaded "go" plug of a length equal to the longest en- 
gagement of work 




Figure 75. Typical Thread Gages — Pratt and Whitney Company 



THREAD-GAGING 



323 



(b) Threaded "not go" plug, made short and with clearance 
for full and root diameters ; 

and for bolt or screw: 

(a) Threaded "go" ring of a length equal to the longest engage- 
ment of work 

(b) Threaded "not go" ring made short and with clearance 
for full and root diameters. 3 



The Hartness Comparator 

Now, the fact is that such gages are blind in the sense 
that the gage covers the work while the latter is being gaged, 
and knowledge must be 
based upon the feel of the 
fit of the gage with the 
work. This might do well 
enough were it not for the 
fact that the work inevi- 
tably carries with it the 
little errors already re- 
ferred to, such as rough- 
ness of the surfaces, chips, 
and slight variations or 
wabbles in the pitch, in 
addition to direct dimen- 
sional variations which are always present. These hidden 
dangers are without doubt at the root of most of the 
aggravating and perplexing troubles so frequently en- 
countered in the assembling of threaded parts, troubles 
which are augmented in marked degree with increase 
in the precision required for neat fits and complete inter- 
changeability. Owing to the conditions just set forth, the 
use of snap and ring gages actually discards some of the best 




Figure 76. Typical Thread Gage — ■ 
Pratt and Whitney Company 



3 "Progress Report of Committee on Limits and Tolerances in Screw-Thread Fits," Me- 
chanical Engineering, Aug., 1018. 



324 



THE CONTROL OF QUALITY 



threaded parts of a lot and accepts some of the worst. Con- 
sequently, even with gages in excellent shape, it is important 
to base our control system on the work itself, since gages of 




Figure 77. General View of Hartness Screw Thread Comparator 



this type are apt to be misleading. Furthermore, it is not 
enough to know that errors exist because we can feel them ; 
they must be brought out into the open and measured be- 
fore we can proceed to correct them with any degree of 
assurance as to final results. Several designs of optical 




Figure 78. Another General View of Hartness Screw Thread Comparator 

projection apparatus have been developed for this purpose, 
both in this country and abroad, and these mark a decided 
advance in apparatus for checking both threaded work and 
thread gages. 

The Hartness screw thread comparator, illustrated in 
Figures 77 and 78, positions the work in a cradle or work- 



THREAD-GAGING 



325 



holder (see Figure 79) , in such a relation to its helix and diam- 
eter as to show the situation at a glance, by visual com- 
parison of the projected outline or shadow with the tolerance 
chart of the screen. 

Internal threads may be checked with the same appara- 




Figure 79. The Work Holder and Projection Lens of Hartness Screw Thread 

Comparator 

Showing a standard plug in the cradle. The machine is adjusted by use of a standard threaded 
plug. The plug is a perfect check that may be used during the run of gaging. 



tus by the use of sulphur casts, after the method long in use 
in measuring the cartridge chambers of small arms. Graphite 
may be mixed with the sulphur (7 per cent of graphite by 



326 THE CONTROL OF QUALITY 

weight) to reduce shrinkage and surface reflection. 4 Or, the 
tap used in threading the hole may be checked. 

There is then made available a simple means for verify- 
ing threaded work (both passed and rejected parts), so that 
errors may be revealed and measured. This apparently is 
the proper starting point for bringing the work under con- 
trol. The same procedure is then extended to correct the 
tool equipment so that it will produce work of the desired 
character ; and finally to check such gages as are needed for 
convenience, being guided always by the principle that it is 
more useful as a measure of a gage's effectiveness to check 
the work which the gage passes than it is to regard the 
absolute measurement of the various elements of the gage 
proper as final and conclusive. 

It may be mentioned incidentally that there is a useful 
field of application for projection apparatus in irregular 
profile and contour work, as well as for threads; but in all 
work with such equipment due attention must be given to 
locating the apparatus away from troublesome vibrations. 

Other Equipment for Measuring Threads 

For a complete description of the equipment employed 
by the Bureau of Standards in measuring thread gages, the 
reader is referred to the paper by H. L. Van Keuren, men- 
tioned above, which may be used as a guide in equipping 
the control laboratory for thread gage-checking. The 
gaging system should be adopted with reference to the 
character of the work to be handled. For precise work the 
optical projector will usually be supplemented by a special 
lead testing machine. An excellent instrument of this type 
was brought to a high state of perfection during the war by 
Major H. J. Bingham Powell, who was Director of the Joint 
Gage Laboratories of the British War Mission and the 

4 "The Measurement of Thread Gages," by H. L. Van Keuren, chief of Gage Section, 
United States Bureau of Standards, in Mechanical Engineering, Nov., igiS. 



THREAD-GAGING 327 

United States Bureau of Aircraft Production. For such 
work the West and Dodge Company's lead tester (see Figure 
8) is often found in the dimensional control rooms of fac- 
tories doing precise work. Similarly, the well-known three- 
wire method for measuring the pitch diameter should be 
provided for by supplying accurate apparatus for this work. 
The method is a most useful one, but requires careful appli- 
cation for accurate results. 

Ordinary ring and plug gages are frequently supple- 
mented in close work by special types of gages, such as com- 
bined lead and diameter gages, using micrometer heads in 
combination with compound levers or dial indicators for en- 
hancing errors in the work — making them appear greater. 
For simple work the ordinary type of screw thread microm- 
eter still has a useful field. 

Thread Gage Tolerances 

There probably is no other branch of gaging which re- 
quires so much attention to the effect of wear as does accu- 
rate thread-gaging, and this, of course, brings in the matter 
of gage tolerances. In this connection Frank O. Wells 5 

states : 

One great difficulty with the business of manufacturing thread 
gages is the unreasonable and useless accuracy of gage tolerance and 
wear allowance sometimes requested by purchasing firms. When a 
tolerance of 0.0002 in. is set on a gage specification it should mean 
that the customer's tolerance on product is as close as 0.001 in. If 
the purchaser's manufacturing tolerance is any broader than that, 
there is no use in keeping the gage so close. A 0.0002 in. error would 
be lost in the comparison. In order to facilitate the making and to 
lessen the cost of thread gages, it is well to allow quite liberal toler- 
ances in their manufacture, and we recommend the following as 
being applicable for most cases where medium tolerances are 
allowed on product: 



5 "Present Practice in Thread Gage Making," by Frank O. Wells, President, Greenfield 
Tap and Die Corporation; member Congressional Screw Thread Commission, in Mechanical 
Engineering, Dec, 1918. 



328 THE CONTROL OF QUALITY 

From 4 to 6 pitch allow a tolerance of 0.0006 in.; from 7 to 18 
pitch allow a tolerance of 0.0004 i n - ! from 20 to 28 pitch allow a toler- 
ance of 0.0003 in. ; from 30 to 80 pitch allow a tolerance of 0.0002 in. 

The foregoing applies to master gages. For inspection 
gages the tolerances would be slightly wider, and would 
begin where the master inspection gage tolerances leave off. 
These would be as follows : 

From 4 to 6 pitch a tolerance of 0.0009 in. ; from 7 to 10 pitch a 
tolerance of 0.0006 in. ; from 1 1 to 18 pitch a tolerance of 0.0004 in - ; 
from 20 to 28 pitch a tolerance of 0.0003 i n - 1 from 30 to 40 pitch a 
tolerance of 0.0003 in. ; from 44 to 80 pitch, 0.0002 in. 

All of the foregoing tolerances would be applied plus in the case 
of go male gages and no-go female gages ; and minus on no-go male 
and go female thread gages. 

The plus and minus tolerances given apply to pitch diameters 
of all thread gages and also to root or core diameters of templets 
or female thread gages. 

The maximum, or go, templet gage represents the maximum or 
basic screw and its manufacturing tolerances should be minus on 
pitch diameter and root diameter. The minimum or no-go, templet 
should be made to plus tolerances with an extra plus allowance on 
the root diameter, which will insure this gage's really checking the 
effective size of the screw. The wear and adjustment tolerance on 
a gage should be coarse or fine on a sliding scale according to the 
manufacturer's tolerance on his product. 

As Mr. Wells shows, the matter of gage tolerances refers 
back to the tolerances required for the work itself. The 
latter subject has received much attention from engineering 
organizations in recent years, and the results of their con- 
clusions as set forth in various publications should have the 
careful attention of manufacturers. 

Precision Depends upon Service Requirements 

It may be noted again that the problems of this subject 
necessitate at the start a determination of the things we 
wish to accomplish with our product. What service are 



THREAD-GAGING 329 

the threaded parts required to perform? What are the 
elements of these parts which make the principal con- 
tribution to the rendering of such service? What variations 
from the ideal for the sake of economy of manufacture is it 
sensible to tolerate without too greatly compromising effec- 
tiveness? When the subject is analyzed in this order, it 
may readily develop that the best results will flow from 
easier tolerances but with closer adherence to these standards 
in the dimension and finish of the product. Thus better 
attention to the quality of the work may permit the gage 
tolerances to be a fifth instead of a tenth of the tolerances 
allowed for the work; especially when the work is more 
positively checked from time to time by independent meth- 
ods, such as by the use of the optical projection apparatus 
referred to. 



CHAPTER XX 
THE PRECISE CONTROL OF PROCESSES 

What Dimensional Precision Is Practicable? 

In the study of dimensional control it is sometimes de- 
sirable to consider what degree of accuracy is commercially 
obtainable for a given job. The logical starting point for 
such an investigation is the examination of the results 
obtained in various processes which are in actual use at the 
time. It should be observed, however, that any such figures 
are subject to correction from time to time as the manufac- 
turing arts are advanced toward greater precision. To be 
sure, a very high degree of accuracy has been obtained in 
certain businesses at the present time, and it would be diffi- 
cult to see any advantage at the moment in further improve- 
ment; but experience shows quite clearly that progress has 
not stopped. As the advantages, both commercial and 
technical, of higher precision come to be recognized, there 
is no doubt that further and even more startling advances 
will be made. 

The manufacture of automobiles has developed a very 
high degree of accuracy on a commercial scale, so that our 
first examples of obtainable precision are taken from that 
industry. In the Lincoln factory, for example, "there are 
more than 5,000 operations in which the deviation from 
standard is not permitted to exceed the one thousandth 
part of an inch, more than 1 ,200 in which it is not permitted 
to exceed a half of one thousandth; and more than 300 in 
which one-quarter of a thousandth is the extreme limit of 
tolerance." The large number of closely held operations in 
this industry has been a matter of frequent and general 

330 



THE PRECISE CONTROL OF PROCESSES 33 1 

comment. It is only a year or two since the Marmon Com- 
pany, for example, at the Motor Show in New York put on 
an exhibition in which two men took down and reassembled 
a complete engine in 1 hour and 45 minutes. Such pre- 
cision kills the need of hand-fitting. 

Automobile Experience 

A former associate, G. D. Stanbrough (in response to 
the author's request), writes the following setting forth his 
experience with precision work in the automobile industry : 

With regard to commercial limits on different forms of ma- 
chine work I may say that at the time a new model is placed in the 
factory ' the limits are carefully gone over by a committee represent- 
ing the Engineering, the Manufacturing and the Inspection Depart- 
ments. The committee sets the limits which the Manufacturing 
Department knows from past experience are commercially possible, 
and yet within the tolerances desired by the Engineering Depart- 
ment. It is our practice to give all information necessary on the 
drawing, as to roughing and finishing dimensions, also, forging and 
casting dimensions. 

It might be well to point out at this time that an understanding 
is not always had as to the matter of limits in manufacturing. The 
matter of design and its relation to limits is quite frequently mis- 
understood and much trouble can be avoided by thoroughly under- 
standing these functions. It should be borne in mind that the de- 
sign of a piece of apparatus involves the strength of materials and 
the appearances. That is, you must have the necessary strength to 
perform the function and to have a finish compatible with the con- 
dition under which the piece is used, or the particular ideas from 
a sales policy that is to be carried out. While on the other hand the 
matter of limits is purely manufacturing and involves the practices 
of the shop in which the work is done. 

It naturally follows that as closer limits are approached in man- 
ufacturing, the design in turn can be improved. An automobile 
manufactured to give satisfactory service over a long life must of ne- 
cessity be built to close limits. Noise probably more than any 
other one cause is responsible for the comparatively short period of 



1 The Packard Motor Car Company's factory is referred to. 



332 THE CONTROL OF QUALITY 

time in which a machine gives satisfaction to the customer. In or- 
der to manufacture an automobile that will give noiseless operation 
over a period of years close limits are essential, and it has been our 
constant aim in designing tools and in laying out our processes to 
decrease our limits. 

To date we are able to hold the grinding on such parts as the 
piston pin, the cam roller pin, and other parts subject to reciprocat- 
ing motion to a limit of plus .000 minus .00025. We are holding 
turning dimensions to plus or minus .0005 — this limit being held on 
bushings and bearings. On milling work we are holding to plus and 
minus .001, in fact we have a 4^2" dimension on our crankcase which 
is held to this limit. On milling key-ways we hold the width to a 
limit of plus or minus .0005. On reamed work we hold to a limit of 
plus or minus .0005 with the exception of the cramshaft sprocket, 
the piston pin bushing, and some other close parts, where by hand 
reaming we hold a limit of plus or minus .00025. 

We are holding today, in the commercial practice of the shop, 
to limits which but a few years ago were only called for on the most 
accurate tool room work. However, this is the result of first class 
inspection methods combined with properly designed jigs and fix- 
tures. 

Of course you realize that in the manufacture of large numbers 
of interchangeable parts, speed in manufacturing can only be ob- 
tained through close limits which give a high degree of interchange- 
ability. Quality can be controlled, if quality is the idea of the 
Management; if the people behind an enterprise have a genuine de- 
sire to get quality and are willing to pay the price, it should be 
borne in mind that it costs money initially to produce quality, to get 
a job up to the highest standard of manufacture. However, once that 
standard is reached it can be maintained cheaper than it is possible 
to maintain a lower standard, owing to the fact that pieces assemble 
with greatly increased speed when fitting in an Assembly department 
is entirely eliminated. 

With reference to the crankshaft and the camshaft, we check 
the overall and intermediate dimensions in a fixture gage which has 
stops at different points, allowing the use of a "go" and "no go" 
feeler. Inspection by this method is quicker and more accurate. 
We find that the twin-six crankshaft supported only on the front and 
rear bearing will not sag anything over night, but in a test covering 
a week's duration we found a sag of .0005. 



THE PRECISE CONTROL OF PROCESSES 333 

It might be of interest to you to know that our Liberty Engine 
crankshaft supported on the front and rear bearing would sag over 
night from .001 to .0015 while the sag in a week would be .003. 
Of course, this was due to the extremely long shaft and a fair degree 
of flexibili ty . However, I do not think that any close comparison can 
be drawn as to the sag of a crankshaft, because so many items enter 
into the consideration, such as: design, material, heat treatment 
of the material, manner in which it is processed, the amount of 
straightening that is done, room temperatures, and consequently tests 
of this kind may be only considered comparatively. Of course, 
comparisons will be useful provided they are made on shafts of simi- 
lar design. This question, however, reaches into technical details 
which are beyond consideration of ordinary inspection practice. 

The tolerances disclosed in these cases are typical and 
indicate the precision obtained in daily manufacturing in 
those motor car factories where dimensional control has been 
carried to the highest practicable standard of achievement. 
Works of this sort employ from 20,000 to 40,000 limit gages, 
whose cost runs into the hundreds of thousands of dollars. 
The inspection of finished parts alone may require 72 hours 
per car. Some other industries apply more gages, occasion- 
ally as many as 50,000 in one factory; but few, if any, 
achieve the precision of the automobile factories, on a 
quantity production basis — day in and day out. With over 
10,000,000 motor vehicles in the country, everyone has a 
chance to familiarize himself with their various parts. 
Consequently, the precision for principal dimensions gives 
a pretty good general idea of commercial possibilities for 
various sorts of machine work. 

Tables of Tolerances 

Another source of information as to precision is to be 
found in tables of tolerances. In a sketch furnished by the 
C. E. Johansson Company, Inc. (see Figure 80), various 
kinds of fits are shown, together with two tables of tolerances 



334 



THE CONTROL OF QUALITY 



Illustrating the Different C /asses of 
fits Repaired fn the Construction 
of a Simple Drill Press - 



l iyht Hunnina Tit 



Running Tit 



Sliding Fit 




Drivincj Tit 



Figure 80. Sketch of Drill Showing Various Fits — Johansson 



THE PRECISE CONTROL OF PROCESSES 



335 



and limits (Figures 81, 82, 83, and 84). One set of data is 
based upon the hole system, in which the hole is taken as 
the reference point of greatest accuracy, and the other is 
based upon the shaft system. Since the recent develop- 
ments in greater precision of work, especially as regards 
grinding, there would seem to be little need of considering 



C E. JOHANSSON 



DIAGRAM OF 

LIMIT SYSTEM 

SHAFT— BASIS 




TOLERANCES: THE SHAFT -100:1. 



Figure 81. Diagram of Limit System — Shaft Basis — -Johansson 



whether we should work from the hole or the shaft, but the 
figures are interesting as a guide nevertheless. 
f' In recent years considerable pioneer work has been done 
in England toward assembling useful data on precision and 
pioneer work of the same sort has started in this country. 
In July, 1920, Mechanical Engineering announced the forma- 
tion of a sectional committee of the American Society of 
Mechanical Engineers for the purpose of studying and re- 
porting on plain limit gage standards and machined fits. 



336 



THE CONTROL OF QUALITY 









o 3 



THE PRECISE CONTROL OF PROCESSES 



337 



The questionnaire prepared by the committee, as published 
in Mechanical Engineering for February, 1921, states that 
the practice of one well-known firm is as follows for various 
classes of fits: 

Class No. i Loose Fits 
Machined fits of agricultural, domestic, and other machinery 

of similar grade (wagons excepted) 
Mining machinery 

Controlling apparatus for marine work, etc. 
Textile and rubber machinery, candy and bread machinery, 

and others of similar grade 
Some parts of ordnance 
General machinery for manufacturing. 

Class No. 2 Medium Fits (Moving Parts) 
2a High Speeds (over 600 r. p. m.) and Heavy Pressures 
Electrical machinery 
High-speed parts of woodworking machines 



C. E. JOHANSSON 



DIAGRAM OF 

LIMIT SYSTEM 

HOLE— BASIS 



TOLERANCES: THE HOLE - IOO:I 




Figure 83. Diagram of Limit System — Hole Basis — -Johansson 



338 



THE CONTROL OF QUALITY 



?a 



£g 



THE PRECISE CONTROL OF PROCESSES 339 

Sewing machines 
Machine tools 
Locomotives 
Printing machinery 
Automotive 
Ordnance 

General machinery for manufacturing. 
A well-known firm uses allowances of 0.0005-0.004 in. up to 6 
in. for work of this class. 

Class No. 2 Medium Fits 
2b Ordinary Speeds (under 600 r. p. m.) and Light Pressures 

Machine tools 

Printing presses and machinery 
Typewriters, calculating machines, etc. 
Locomotives 

Automotive — general parts 
Textiles, rubber machinery 
Ordnance 

General machinery for manufacturing. 
A well-known firm uses allowance of 0.0005-0.0025 in. up to 6 
in. for work of this class. 

Class No. 3 Snug Fits 
(Designated as the closest fit that can be assembled by hand.) 
3a Slight Allowance (0.00025 to 0.00075 in.) 

Gear trains and change gears for general work 

Mating parts, fixed or not, moving on each other, such as 

studs for gears and levers, keys 
General machinery for manufacturing. 
3b Close Fit (commonly known as wringing fit, no allowance, 
not considered interchangeable manufacturing but selec- 
tive assembling) 
Crankshafts 

Precision-ground machine spindles 
Gears in index train of precision gear-cutting machines 
Slots and tongues such as are used for grinding machines, 

milling machines, etc. 
Surveying and scientific dental instruments, etc. 
General machines for manufacturing. 



340 THE CONTROL OF QUALITY 

Class No. 4 Tight Fits 
4a Drive Fits for Light Sections 
Automotive 
Ordnance 

General machines for manufacturing. 
A well-known firm uses negative allowance from 0.00025 to 
0.00 1 in. up to 6 in. 
4b Force Fits for Heavy Sections 
Locomotive and car wheels 
Crank disks, armatures, flywheels 
Automotive 
Ordnance 

General machines for manufacturing. 
A well-known firm uses negative allowance from 0.00075 to 
0.005 m - U P t0 6 in. 
4c Shrink Fits 

Locomotive tires and similar work 
Ordnance. 
A well-known concern's practice is as follows: Where thickness 
exceeds 3/8 in., 0.0005 to 0.005 m - U P to 6 in. in diameter. Where 
thickness is less than 3/8 in., up to 6 in. in diameter, 0.00025 in. to 
0.0015 in. 

It is to be hoped that this committee will cover the field 
of practicable precision of machining processes in consider- 
able detail, and that this data will be kept up to date for 
the guidance of industry. 

Precautions for Obtaining Precise Work 

Among the general considerations to which attention 
should be given in bringing processes under control, one of 
the most evident, but one of the least observed, is to make 
the tool set-up a fool-proof one. There is so much need of 
all available time, care, and attention to details in close 
work that everything which can be done to free the operator 
from unnecessary strain in these particulars should be done. 
Not once but several times during the last years, the writer 



THE PRECISE CONTROL OE PROCESSES 341 

has heard superintendents or engineers say something like 
this: 

We can't seem to get results in the .... shop, and it is due to 
nothing but the foremen's failure to handle their men so as to get the 
answer. I know that the tools and gages are O.K., because I have 
made the complete part myself. Only yesterday I carried a piece 
through each operation personally and it came to the gages in fine 
shape. That proves everything is all right except that the shop 
executives don't exercise proper control over production. 

As a matter of fact it proves nothing of the sort. All 
it does prove is that a skilful mechanic with years of experi- 
ence can make a good part with the facilities provided. 
We knew that already. It has been done before. 

Having detected the fallacy in the above remark, let us 
consider some of the things that such a test does not prove. 
In the first place, such a test does not show that unskilled 
operators can produce good work with the available equip- 
ment, nor does it prove that they will do so, especially if the 
wage system is such as to create a strong incentive for quan- 
tity of individual output. Most large-scale enterprises are 
conducted in a way to place a heavy emphasis on quantity of 
output. Nor does it indicate that the gages will be applied 
correctly by unskilled inspectors, nor that the available 
machine-setters and adjusters are trained to their work, nor 
that the shop arrangements and system are suitable for the 
general conditions as they exist in fact. In short, we are 
faced with a condition and not a theory. The solution lies 
in shaping everything to the actual environment. We must 
deal with things as they are, not as they used to be, or as 
they might be under different circumstances. 

There is a way to meet the situation. When a task calls 
for greater skill than the available labor possesses, split the 
task into simple operations, any one of which will be within 
the capacity of such labor. This is the old, well-known, 



342 THE CONTROL OF QUALITY 

thoroughly tested, but little appreciated, cure for the con- 
dition — namely, a judicious application of division of labor. 
Similarly the principle of analyzing everything into simpler 
parts must be used to the end that each man's work will be 
well within his capacity, for it is through these men that the 
result will be achieved, and only through them. This simpli- 
fying process must be used in every element of the project — 
tools, gages, shop arrangement, shop systems, and organiza- 
tion. This much is axiomatic; nor should it be forgotten 
that such a differentiation greatly complicates the problem 
of co-ordinating the different constituent parts of the work. 

In the second place, the tool and gage designers can 
help safeguard standards by eliminating process hand-work 
as much as possible, and by simplifying the tool and gage 
designs in so far as is practicable. Tool equipment should 
be simple and much more rugged than heretofore. Forcing 
light work should be made difficult. The factor of careless 
machine operation should be discounted by skilful designing 
for chip clearances and bedding points, because careful plac- 
ing of work cannot be counted upon. The same line of 
thought applies to gages — the complicated gage with sev- 
eral gaging points, flush pins, etc., should give way to single 
measurement limit gages. Adjustable limit gages can be 
used to great advantage. In some cases working gages 
should have closer limits than salvage gages, but this is a 
practice that must be settled with reference to individual 
problems. Templates of form, outline, or profile should be 
preserved systematically and checked methodically for both 
cutters and gages. In this checking there should be em- 
ployed the most sensitive tactile skill obtainable. 

In the endeavor to make things fool-proof — a process 
in which nothing must be taken for granted and every detail 
carefully considered because the effect of such details is 
multiplied enormously through repetition, so that little 



THE PRECISE CONTROL OF PROCESSES 343 

things determine results — there is usually no occasion for 
continuing to worry about such matters as keeping the 
bedding points free from chips. A little care in the design 
of the tool will permit chips to fall away from the work in- 
stead of onto the bedding surfaces. Very often an auxiliary 
device may be provided for blowing the chips away auto- 
matically. 

The work itself, as well as the tool, should be designed 
so as to reduce the chance of error from forcing a tool and 
so as to permit accurate holding of the work when it is pre- 
sented to the tool. It is good practice when possible to 
work from holes as locating points for a series of operations. 
The objection to this practice for many operations lies in 
the fact that the work is soft for machining, and the holes 
wear. A little ingenuity will avoid this trouble. Very 
frequently a false hole or slot may be created in the place 
where the metal will be cut away later. When this cannot 
be done, there seems no reason why holding lugs cannot be 
added to the part, hollow-milled in a jig, used for bedding 
points throughout the machining, and finally cut off. In 
fact, there are cases where this has been done. 

The Principle of Balance 

For very careful and accurate control of a process used 
in creating a uniform product, a nice balance should be 
provided, as a direct and practicable application of Newton's 
third law of motion — "action and reaction are equal and 
opposite." Now in a machine tool the whole supporting 
structure which presents the work to the tool should provide 
a wall against which to build up the pressure imposed 
by the tool itself. In laying out the equipment for any proc- 
ess this principle should be carefully considered if a nicely 
balanced application of force must be made. The same 
idea is applicable in many other processes where irregular 



344 THE CONTROL OF QUALITY 

or jerky action may be avoided by balancing the opposing 
forces. 

When difficulties are encountered in bringing processes 
under uniform control, one good way of deciding whether 
the method is correct is to carry it to the extreme in the 
opposite direction. Thus, Professor John E. Sweet states: 

To demonstrate that this is right, a good way in this, as in most 
mechanical problems, is to carry the wrong way to an extreme and 
note the consequences, and it will be found that the right way has 
already been carried to the extreme in the right direction. 

The Effect of Finish on Accuracy 

One of the most important points to be observed in in- 
structing machine operators is care of the work. Attention 
to quality brings about the creation of finer work and that 
of itself usually demands respect ; nevertheless our factories 
are full of workmen who would treat bricks with much more 
respect than they do steel parts — bricks would break if they 
were thrown around, whereas steel parts only become 
dented. But dents and scratches require more polishing, 
more grinding, and uniformity of dimension is lost. On the 
machine itself one way to insure greater uniformity is to 
remove vibration, but this is merely another application of 
the principle of balance referred to above. To meet the 
same condition, it is probable that finishing operations, 
such as automatic polishing and tumbling, will see wider 
application and greater refinement in the future because of 
their marked advantages. 

Quick Checks on Precision 

It will be found useful, from time to time, to apply the 
method of taking check "borings" in the factory, in order 
to develop additional information as to what requires cor- 
rection for greater uniformity. It is suggested, for example, 



THE PRECISE CONTROL OF PROCESSES 345 

that some important part be independently checked and 
measured, beginning with the tools and gages and conclud- 
ing with the measurement of the parts themselves, proceeding 
from operation to operation straight through to the com- 
pletely assembled mechanism. There are other quick tests 
which may be applied. For example, a check on the uni- 
formity of heat treatment may be obtained by supporting 
like parts in like positions for the same length of time and 
measuring their sag. It was in connection with getting 
data for such a test to check up the work of a certain factory 
that the information relative to sag of crank-shafts (referred 
to on pages 332 and 333 of this chapter) was obtained. 
The work as performed in the Packard shops was taken as 
standard in comparing work in a somewhat similar shop do- 
ing cruder work and located many hundreds of miles away. 
The results were very interesting indeed, because of their 
divergence and lack of uniformity. 



CHAPTER XXI 
THE CONTROL OF COLOR 1 

Application of Measurement to Other Qualities 

Up to this point we have dealt with dimension as ex- 
emplifying cases where excellent means of measurement 
exist. Very often in such work special tool equipment is 
provided which works from a pattern made with the 
greatest care, the tools almost automatically following this 
pattern over and over. Even in the case of straight ma- 
chine work without special tools, a high degree of precision 
is possible. Many other processes, however, have not yet 
been regulated with such precision. Bringing them under 
uniform control involves the process outlined in Chapter 
XIII, "Measurement and Errors," but before we are in a 
position to tabulate the various errors in the work produced 
by such operations or processes, it is necessary to develop 
some systematic method of recording both the kinds of 
errors and their relative occurrence both as to frequency 
and size. Color is a typical instance of this general class of 
work — a class which is extremely large in industry today, 
but which will be gradually reduced and brought under 
control as time goes on and the fight continues for greater 
production of better and more uniform qualities at a lower 
expenditure of effort. 

In discussing the subject of measurement in Chapter 
XIII, it was shown that the control of any quality depends 
upon measurement as a starting point, and that measure- 
ment itself is a process beginning with the selection of an 

1 For an authoritative and most interesting treatise on the subject of color, the reader is 
referred to "Color and Its Applications," by M. Luckiesh, Director of Applied Science, Nela 
Research Laboratories of the National Lamp Works, General Electric Company, 

346 



THE CONTROL OF COLOR 347 

arbitrarily chosen sample which is suitable as a standard of 
comparison for the quality under consideration. The next 
stage consists in developing a scale of values to permit 
measures of the quality to be stated in figures, and the final 
step is the development of impersonal measuring instru- 
ments. Dimension and weight, for example, have reached 
the last stage and very precise instrumental means are 
available for control purposes. Many other qualities, 
however, have barely reached the first stage of control by 
direct comparison with standard samples. 

Appearance and Color 

Of the several qualities that define the character of the 
factory product, certainly appearance is not the least im- 
portant, and throughout a wide range of industries color is 
one of the important, if not the most important, quality 
which goes to make up appearance. Frequently, as in the 
case of chemicals and food products, color is an indication 
of other qualities in addition to appearance. Just how 
valuable a uniformly good color is as a commercial asset 
must be decided in the light of the special business situation. 
If color is worth controlling to a commercially uniform 
standard, then, as in the case of the qualities of dimension 
and form, we must define the standard which is to be fol- 
lowed, adopt processes for its creation that are uniformly 
controllable within the limits set, and provide a means of 
comparing the results by some suitable method of measuring. 

Now measurement, as we have seen, is the proper start- 
ing point, and this involves the selection of a standard for 
comparison. If the standard is one which permits com- 
parisons in figures, like the standard of length, so much the 
better. Then, instead of saying that an article is "slightly 
red" or a "little too green," we should be able to say how 
red it is, or how much too green. In that event we might 



348 THE CONTROL OF QUALITY 

hope to do with color what we have already accomplished 
with dimension, by working out the relationship between 
cause and effect. When it became possible to measure in 
ten-thousandths of an inch, we were presently in a position 
to work to that degree of accuracy — but not until then. 
Hence, in the case of color, the first step is to search for a 
proper basis of establishing such a standard of measurement. 

Standard Samples 

The simplest scheme would be to select a series of samples 
of the goods and grade them according to an arbitrary scale 
with reference to their appearance. Thus, ten samples ar- 
ranged in a scale, in which each one differed from its neigh- 
bors by an equal amount of color, or luster, or smoothness, 
would provide us for comparative purposes with a scale of 
ten. Sometimes, a simple scheme such as this is all that con- 
ditions warrant, or perhaps it may be the best we can do; 
but it is entirely too coarse for precise and careful work. 
The lack of quantitative comparison greatly hampers any 
systematic attempt to evaluate deviations from standard 
and therefore to develop means for correcting such errors. 

The Standard Color Card 

The first movement in our industries for standardizing 
color for commercial purposes was made by The Textile 
Color Card Association of the United States, in developing 
a series of color cards which find wide use in most of the in- 
dustries engaged in the manufacture of clothing and the 
basic materials of clothing. The fact that the paint, paper, 
and some other - industries are making use of these color 
cards indicates their great practical value in reducing losses 
of various sorts. A numbering system is used in accordance 
with the following scale, standard colors being indicated 
by the letter S used as a prefix: 



THE CONTROL OF COLOR 349 



st, 2nd, 3rd figures in 


dicate the rela- 


4th figure in 


dicates the strength of the 


tive proportion of 


the component 


color designated by the first three 


parts of a color: 






figures: 




1 


White 






1 


Lightest 


2 


Red 






2 


Second lightest 


3 


Orange 






3 


Light 


4 


Yellow 






4 


Medium light 


5 


Green 






5 


Medium 


6 


Blue 






6 


Medium dark 


7 


Violet 






7 


Dark 


8 


Gray 






8 


Second darkest 


9 


Black 






9 


Darkest 





No chai 


ige 










To 


illustrate: 


Turquoise is "S. 


6i53" 


6 




1 




5 


3 


Blue 




White 




Green Light 


Principal 




Principal 




Secondary Strength 


Color 




Blend 




Blend 





The establishment of this systematic classification of 
colors for commercial purposes in the textile and allied 
industries is evidence of a highly commendable and far- 
sighted attitude toward solving the problem of color con- 
trol. It will be noted, however, that in its last analysis 
any such classification depends upon the integrity of the 
standard samples supplied by the color cards themselves; 
the samples on the various cards must be alike for a given 
color, and each sample should be as little likely as possible 
to change as time goes on. The necessity for such assump- 
tions can only be offset when the art has been advanced to 
a point where construction formulas for the reproduction of 
standard colors can be stated in terms of the exact propor- 
tions of the color-creating factors, and the colors them- 
selves can be stated in impersonal figures. 

A similar practical contribution towards color standard- 
ization was made by the late A. H. Munsell in the form of a 
color notation and an atlas of colors. 2 The atlas consists 



1 A. H. Munsell, "A Color Notation"; "The Atlas of the Munsell Color System." 



350 THE CONTROL OF QUALITY 

of a series of charts in which colored samples are arranged in 
accordance with the Munsell color system. A scientific 
investigation of this system was undertaken by the Bureau 
of Standards and a very interesting report of it is published 
under the title of "An Examination of the Munsell Color 
System." 3 

Dangers of Standard Samples 

The great trouble with standard samples is that we have 
no assurance that they are not continuously changing. 
On the contrary, we can be sure that they do change, and 
by such insidiously small increments that the changes are 
hard to detect. The sample is one thing today and some- 
thing else almost before we know it. More dangerous yet, 
we may not know that its appearance has altered. In 
many plants where this is fully appreciated master stand- 
ards are kept. When it is the custom of the color expert 
to carry in his mind and to allow for any slight difference 
between the working and the master sample, the practice 
usually leads to interesting results. 

Just as in the case of dimension, precise control of color 
requires a more absolute method of measurement. But to 
fix upon that, we must first get some idea of what makes 
color. Perhaps this would be expressed better by saying 
that our first problem is to determine, as nearly as we can, 
what color is. 

What Is Color? 

If a truism may be pardoned, color (and for that matter 
any quality which goes to make up appearance) is some- 
thing which you see with your eyes. What else can it be? 
And the eye is sensitive only to light. It makes no differ- 



3 Bureau of Standards, "Technologic Paper No. 167," by Irwin G. Priest, K. S. Gibson, and 
H. J. McNicholas. 



THE CONTROL OF COLOR 351 

ence whether the particular kind of appearance we are deal- 
ing with is caused by a mechanical treatment of the surface 
of the article, or by stains, pigments, or dyes, or whether 
the subjective sensation of color is due to some inherent 
property of the raw material from which the article is 
made. But irrespective of the cause of color, the effect is 
light, so that as a starting point the use of optical methods 
is indicated at once as the only sure way of attacking the 
problem, both for standardizing the final result and for 
measuring the effects as a step toward controlling the agents 
used to create that result. Thus, color considered as the 
final effect must be reduced to a measured basis for com- 
parison with a view to studying the causes of errors or 
differences, as well as the means for modifying errors and 
making the results more uniform. 

In approaching the subject, then, from the standpoint 
of color considered as light, it should be observed that three 
principal factors are involved, since without any one of 
these three there will be no color — first, the illuminant, or 
source of light, which may be regarded as the effector; 
second, the subject, or the thing which is said to have 
color; third, the eye of the observer, which, as the receptor 
of the sensation, is merely a lenticular instrument adjust- 
able within limits but varying from individual to individual 
and from time to time even for the same individual. Let us 
now consider each of these subjects separately. 

The Illuminant 

The sensation of light is now generally considered to be 
caused by a form of radiant energy which occurs in a va- 
riety of wave lengths and frequencies of vibration, but 
which passes through empty space without appreciable 
change in velocity. The nervous system of the eye is 
sensitive to this radiant energy only within a comparatively 



352 



THE CONTROL OF QUALITY 



narrow range, as indicated in Figure 85. 4 Beyond this 
range, in one direction, are found the ultra-violet rays, 
whose presence is made known by their chemical or actinic 
properties. In the other direction are the infra-red rays, 
which are noticeable on account of their heating effect. 
It will be noted also from the relative visibility curve 



1.00 






















1.00 


0.90 






















0.90 


0.80 






















0.80 


0.70 








If 














0.70 


0.60 








**■/ 














0.60 


0.50 








1 

■SI 
a;/ 














0.50 


0.40 






















0.40 


0.30 






















0.30 


0.20 






















0.20 


0.10 






















0.10 


0.00 






















0.00 



380 420 460 

Ultra- Violet Violet Blue 



500 



540 580 620 

Green Yellow Orange 



660 



700 
Red 



740 780 

Infra-Red 



Figure 85. Chart for Spectral Analysis of Color Showing Relative Visibility 

Curve 



(Figure 85) that the eye is not equally sensitive to all the 
visible rays, but that these rays begin to become visible at 
the edge of the ultra-violet region, reach a maximum effect 
in the greens and yellows, and then gradually fade away and 
disappear at the beginning of the infra-red region. 

Since radiant energy is transmitted in the form of 
waves, and since each wave length of the visible rays is 
associated with a very definite color sensation, we have a 



4 This follows the chart used by the Bureau of Standards in the Munsell color examina- 
tion already referred to. 



THE CONTROL OF COLOR 353 

convenient way of exactly indicating any particular hue 
due to a given wave length, or a small group of similar 
wave lengths, by stating that wave length in figures. This 
is especially useful since the eye itself is capable of a very 
sensitive differentiation between the various wave lengths. 
The lower scale of Figure 85 shows the wave lengths as- 
sociated with the principal colors. The figures stated for 
wave lengths are in millimicrons, or millionths of a milli- 
meter (about a 25-millionth of an inch). 

White light is, of course, a mixture of all these rays in 
more or less definite proportions, depending upon the 
source of light. For practical purposes it may be taken as 
the effect on the eye of average noon daylight. It should 
be noted also in this preliminary summary that daylight 
itself is varying all the time and from place to place. Con- 
sequently, it is usually anything else but pure white light. 
This fact must be remembered in connection with any 
careful work with color for the reason that, no matter what 
the subject is, only such color can be seen as has correspond- 
ing colored rays in the source of the illuminant. Thus, a so- 
called green surface, which reflects only green light, if illumi- 
nated by a red light will appear black, because no light is 
reflected. Consequently, the importance of having a stand- 
ard illuminant for color work becomes obvious, and as it is 
merely common sense to keep all of our work in consonance 
with the ordinary conditions with which we are acquainted, 
a light source as nearly as may be like natural north sky 
daylight is generally taken as most suitable for color-match- 
ing and study. Such lights are obtainable commercially 
and are made by filtering out the rays which are in excess of 
those contained in average north sky daylight. When the 
light is reflected for instrumental use, it is the usual practice 
to employ a white magnesia block or some equivalent, as 
the standard white for comparison. 



354 THE CONTROL OF QUALITY 

The Subject 

In studying the characteristics which cause an object to 
have color, let us consider the limiting cases first. A per- 
fect mirror would reflect practically all of the light from the 
illuminant and the result would be the same as looking at 
the illuminant. At the other extreme, a perfectly black 
surface would absorb all of the light and reflect none. If 
the object, on the other hand, reflected only a portion of the 
incident light without changing the relative distribution of 
the constituent light rays, the color of the object would not 
be different from that of the illuminant, but it would be less 
bright. Thus, if the illuminant were a white light the object 
would appear gray. We have now defined white light or 
white, black or the absence of light, and the neutral grays, 
as intermediate stages between the two extremes of white 
and black. 

Suppose, however, the subject does not equally reflect all 
of the incident rays, but that it absorbs some of them and 
reflects the remainder. This process of selective absorption 
and reflection brings about an unbalanced distribution of 
the light rays as compared with the normal distribution in 
white light, with the result that some one group of rays 
becomes dominant. For example, if a red predominates 
in the light reflected by the subject, we say that the subject 
is colored red. 

If the subject is a fluid, essentially the same process of 
selection takes place, except that in this case certain rays 
are absorbed and others transmitted so that we have selec- 
tive absorption and transmission. That is to say, the words 
used are different, but the ideas are identical. 

Color is caused in several other ways, such as by the 
interference of light rays (as for example, by a drop of oil on 
water) , or by dispersion of light (with a prism) , or as in the 
case of fluorescent and phosphorescent substances, or by 



THE CONTROL OF COLOR 355 

polarization, to mention a few instances of color phenomena. 
In industrial work, however, selective absorption is by far 
the most frequently encountered. 

The Eye 

For our present purpose the eye may be considered as 
an optical instrument of lenticular form which is the inter- 
mediary between the brain and the external causes of light 
and color. The eye views a group of colored rays, or rays of 
different wave lengths, solely as an intermingled group and 
sees only the average result of the mixture, e.g., white light. 
In this sense it is a synthetic instrument incapable of ana- 
lyzing the light presented to it, or of separating out the in- 
dividual rays. In order to accomplish such analysis, the 
eye requires the assistance of an instrumental device such 
as the prism, or the ruled grating, or a color filter, as will be 
shown presently. Without such a device it is impossible to 
view the constituent colors of any mixture separately. 
Thus when one mixes a blue powder with a yellow, the eye 
presently sees only the green effect of the combination. 

The Color Constants 

On the other hand, the eye can analyze color with ref- 
erence to three so-called color constants known under vari- 
ous terms as set forth below. Says Dr. M. Luckiesh: 

One of the greatest needs in the art and science of color is 
a standardization of the terms used in describing the quality of 
colors and an accurate system of color notation. . . . The 
quality of any color can be accurately described by determining 
its hue, saturation or purity, and its brightness. 

Hue (sometimes called ' ' color tone " or " quality ") is the 
kind of color with reference to the spectral color scale. Thus 
a color whose predominating group of rays are in the red is 
said to have red as the dominant hue. When color is 



356 THE CONTROL OF QUALITY 

measured instrumentally the dominant hue is stated in 
figures as the wave length of the spectral color correspond- 
ing to the dominant hue. The hues of the non-spectral 
purples are handled by taking the dominant hues of their 
complementary 5 colors. 

Purity (also called "saturation," "chroma," "strength," 
or "intensity") indicates how closely the constituent rays 
approximate to none but rays of the dominant hue. Spec- 
tral colors are pure, but other colors are composed of many 
other rays than those which predominate — hence the purer 
the color, the nearer it is in composition to the spectral color 
of corresponding hue. 

In instrumental measurements of color, since any color 
may be matched by diluting a given spectral color with 
white light, the relative quantity of white light required for 
the match is used as the measure of purity and is expressed 
in .figures as a percentage. The purity becomes greater 
as the percentage of white light required for a match be- 
comes less. As stated under "hue," purples form an excep- 
tion, but these are handled by working in terms of the cor- 
responding complementary colors. 

Brightness (also called "luminosity," "value," or 
"tone") relates to the total amount of light reflected or 
transmitted, regardless of hue or purity — thus a neutral 
gray photograph of colored objects shows variations in 
brightness only. It is measured by comparing the subject 
with a surface of known brightness, the result being ex- 
pressed as a percentage of the standard of brightness. 

The ideas conveyed by the above definitions will be clar- 
ified by referring to the graphs shown in Figure 86. Curve 
a is a gray because it contains equal proportions of all the 
special colors and differs from white only in reduced bright- 
ness. Curves b, c, and d, are all colors of red hue, of which d 

5 A complementary color may be denned by stating that when white light is split into two 
parts the colors thus formed are complementary to each other. 



THE CONTROL OF COLOR 



357 



is the brightest, since it reflects the most light, and c is the 
purest because it has the least admixture of other rays 
than red rays. Curve e is a blue. Differences in purity 
may be accentuated by plotting the curves on logarithmic 
paper. 

Tints are formed by diluting a color with white, i.e., by 
reducing the purity; e.g., spectral colors are pure — pinks, 



1.00 






















1.00 


0.90 






















0.90 


0.80 






















0.80 


0.70 








■SI 










-a 




0.70 


0.60 






















0.60 


0.50 


d — 






-5/ 

of 
°7 














0.50 


0.40 






















0.40 


0.30 


e — 




















0.30 


0.20 


















—e 




0.20 




























c— . 




















0.10 









0.10 




6-^. 






















0.00 










0.00 



380 420 460 

Ultra-Violet Violet Blue 



540 580 620 

Green Yellow Orange 



700 
Red 



740 780 

Infra-Red 



Figure 86. Chart for Spectral Analysis of Color Showing Typical Color 
Analyses Plotted as Curves 



which are tints of red, are not found in the spectrum. Shades 
are produced by admixing black, i.e., by reducing brightness 
without affecting hue or purity. 

The above facts are of interest in the practical study of 
color, for the reason that it would seem desirable to analyze 
and measure color in terms of the dimensions, such as hue, 
purity, and brightness, which the eye is capable of seeing 
without instrumental assistance. This would appear to be 
the natural way to approach color problems instead of 



358 THE CONTROL OF QUALITY 

using some system of combining primary colors, but in 
either case practical difficulties must be overcome in any 
given industrial application. 

Color Vision 

As might be expected, the human eye is quite variable 
in the way in which it sees color. It varies from time to 
time with the same individual and very seriously from in- 
dividual to individual. The lack of a definite and precise 
terminology for color among the general public has resulted 
in a looseness of usage which accentuates this source of per- 
sonal error. Many cases of so-called color blindness have 
been found to be nothing but lack of education of the eye. 

The eye of a highly trained color expert or matcher is 
extremely sensitive to very small color differences and dis- 
tinctions. This fact is, in the writer's opinion, one of the rea- 
sons why color in the arts has not been reduced to a basis of 
measurement to any considerable extent, outside of the 
physics laboratory. The chemistry of dyestuffs and pig- 
ments has received very intensive study, because for their 
intelligent application such study has been absolutely nec- 
essary ; but the very ability to perceive small differences in 
the color effects resulting from the use of such tinctorial 
agents has lead to ignoring the very desirable and vitally 
important features of measurement. Thus, in the factory 
one hears such expressions as the following: "The color is 
a little too much on the red" — " It has a slight red cast" — 
" It is too fine"— "Too nice"— "Too quiet"— "Not enough 
depth" — and so on. The absence of any means for quan- 
titative measurement, or the failure to develop and utilize 
means for stating in figures how much these color errors are, 
has stood in the way of progress toward finding out the 
proper adjustments and corrections of processes so that 
they could be standardized. 



THE CONTROL OF COLOR 



359 



Methods of Analyzing Color 

Color can be analyzed for purposes of study in much the 
same way that it is created, if use is made of various devices 
which break up light into its constituent parts. Thus, dif- 
fraction by the use of a parallel-ruled grating is one means 
which may be used, but the best known device is a simple 
prism when used as a means of dispersion. As shown in 
Figure 87, light rays of different wave lengths bend differ- 




Figure 87. Sketch of Prism and Spectrum 

ently in passing through a prism of glass of triangular cross- 
section and thus are dispersed in a systematic way. The 
consequence is that the rays of different wave length are 
separated so that viewing a ray of light which has been 
dispersed by a prism shows a band of separate colors which 
is known as the "spectrum." 

In other words, each color in the spectrum' is a small 
group of light of similar wave lengths and is the nearest to a 
truly pure color to be found in nature. It is for this reason 
that purity, as defined on page 356, is expressed as a per- 
centage, indicating its nearness in this respect to the spectral 
color of the same hue, and showing its degree of freedom 
from all other colors except the dominant hue. 

The use of a simple piece of glass to produce a spectrum 



360 THE CONTROL OF QUALITY 

should be a constant reminder that the world is not only 
given to us as a great problem to solve, but also that the 
means of working out the problem are at hand and in fact 
very often exist in very simple and readily accessible form. 
Who would suspect that the ordinary white light of a gloomy 
day contains the hidden beauty which is to be found only in 
the pure spectral colors? The eye cannot see them with- 
out the assistance of very simple means, yet it was not until 
1666 that Sir Isaac Newton used the prism to create a rain- 
bow at will. 

Analysis by Primary Colors 

Color may be analyzed also by allowing light to pass 
through monochromatic filters. Viewing a subject or, 
more properly speaking, the ray of light from the subject 
through a filter (of stained glass or gelatin) which allows 
only green to pass, will give a very good idea of the amount 
of green present. Similarly, the use of other color filters per- 
mits a more complete analysis. Further, as is well known, 
it is possible to match any hue with a suitable combination 
of three primary colors. There are two or three things to 
remember, however, when speaking of primary colors. 
First, since the eye is an averaging instrument, there are 
several combinations of three colors which will yield the 
same result to the eye although upon analysis the spectral 
composition would prove to be quite different in each case. 
In other words, the same effect may be brought about by 
mixture of different sets of carefully selected colors. 
Second, colored lights may be mixed by addition of colored 
light rays and each addition tends toward the production of 
white. This will be evident from a consideration of the fact 
that white light itself is the summation of all the colored 
rays. The "additive" primaries are red, green, and blue. 
Third, color as ordinarily produced in the arts is the result, 



THE CONTROL OF COLOR 36 1 

on the other hand, of the successive subtraction of light, due 
to the fact that each stain, dyestuff, or pigment selectively 
absorbs some of the incident light. Consequently, as Pat- 
erson 6 says, "every admixture of colour is a step towards 
darkness." The " subtractive " primary colors are ordi- 
narily termed red, yellow, and blue. Luckiesh states, how- 
ever, that they would be more exactly described as purple, 
yellow, and blue-green. These subtractive primaries are 
what most people ordinarily call the primary colors. As a 
matter of fact, they are only primaries for color-mixing of 
stains, pigments, and dyes. They are, moreover, the com- 
plementaries of the additive primaries for mixing colored 
lights. 7 

Instruments for Measuring Color 

A large number of instruments for analyzing and meas- 
uring color are in constant use in the physics laboratory. 
These instruments are based on various adaptations of the 
principles outlined above. Although some of them have 
been employed in the arts, their main use has been in labora- 
tory work. In general, they have not been used to any- 
thing like the extent that the resultant economies to be 
obtained from their application would warrant. This is 
partly owing, as already stated, to the failure of manufac- 
turers to realize the vital importance of measurement in 
bringing some of our long-established processes under more 
precise technical control, and partly owing to the fact that 
some of the instruments require modification to make them 
more suitable for general industrial use, as will be presently 
indicated. 

Basic control instruments belong to the spectrometer 
class. Some of them look quite complicated, but they really 



6 See David Paterson, "Textile Colour Mixing," p. 34. 

7 "Color and Its Applications," by M. Luckiesh, Chapter III. 



362 THE CONTROL OF QUALITY 

consist of a simple application of some equally simple optical 
parts. A prism (or sometimes a grating) is used to break 
light up into its constituent colored rays, lenses mounted in 
telescopes are used to magnify the image of the spectrum 
thus created by the prism, and these elements of the instru- 
ment are mounted in such an adjustable relation to each 
other that a scale can be marked off on the instrument to 
show the wave length of each color. To accomplish the 
latter purpose, either the telescope or the prism is revolved 
to bring each spectral color into the viewing axes, and the 
corresponding wave length is shown on a calibrated scale. 

The Spectrophotometer 

The spectrophotometer is an instrument for breaking up 
light from the subject into its constituent rays (this is the 
spectroscopic part of the instrument) and for measuring the 
quantity of each part of such light against, or as a percent- 
age of the same rays from a standard white light (this is 
the photometric part of the instrument). Obviously, by 
reason of the fact that it measures the relative quantity of 
each colored ray present in any light, the spectrophotometer 
is the basic control instrument for color. As shown in Figure 
88, it consists of two spectroscopes mounted so that the 
intensity of rays of like wave length in the two spectra can 
be compared by placing them side by side in the field of 
view. Light is taken from a standard source S and from 
the subject .Si. The two rays enter a Lummer-Brodhun 
photometer cube so arranged that after being dispersed by 
the prism they may be viewed in juxtaposition through the 
telescope. It is thus possible to select one spectral color 
after another and by the use of a flicker or other type of 
photometer, to measure the quantity of said color as a per- 
centage of a standard spectral color. 

The result obtained is more clearly shown by reference 



THE CONTROL OF COLOR 



363 



to Figure 86, in which the curves of several spectrophoto- 
metric measurements are plotted. 

The Monochromatic Colorimeter 

As has been seen, the spectrophotometer gives us a com- 
plete analysis of any color, and when the results are plotted 
graphically it is possible to get a very fair idea of the domi- 
nant hue, the purity, and the brightness. To measure 
hue, purity, and brightness of a color in terms of figures 
directly and without computation requires, however, one 
other instrument, which may be regarded as the second 
basic control instrument, known as the monochromatic 



S j— Light from Subject 



Photometer 
Cu be which 
results in a 
Field of Yiew 
as below. 





Figure 



-^S— Standard Light 



"&> Eye of Observer 
Diagram of Spectrophotometer 

(After Luckiesh) 



364 THE CONTROL OF QUALITY 

colorimeter, of which the Nutting colorimeter (made by 
Adam Hilger, Ltd., London) is doubtless the latest and best 
known type. It consists essentially of a spectrophotometer 
with an additional arm to permit the admixture of a known 
amount of white light. Briefly stated, the hue of the sub- 
ject is matched by varying the angular position of one arm, 
the purity is matched by varying the amount of white light 
added, on the principle that any hue can be matched by 
mixing white light in suitable proportion with the corre- 
sponding spectral hue, and the brightness is measured by 
the photometer attachment. 

By means of these two instruments it is possible com- 
pletely to analyze a color, and to state the color in terms of 
figures for the constants, hue, purity, and brightness. Need- 
less to say, the use of figures as a measure of color in the arts 
should be accompanied by the use of plus and minus limits, 
as in dimensional work. Quality varies in the case of color 
just as it does in dimensional work, and the same phenomena 
must be met by practices alike in principle. The precision 
used will vary with the character of the commercial require- 
ments for the given case and with the economic and techni- 
cal possibilities of the processes. 

The spectroscopic type of instrument is available for 
control laboratory purposes. This apparatus may be used 
as a guide in the control of quality of basic materials, such as 
dyestuffs and pigments, and for the completed product, 
with this qualification that many of the colors used in the 
arts are what are known as "mode" or "fashion" colors, 
most of which are quite dark. A great many textiles, for 
example, reflect less than 5 per cent of the incident light and 
it is difficult to get precise measurements with instruments 
which themselves absorb a quantity of light in the optical 
parts. A sufficiently intense demand from the arts will 
doubtless bring about the development of instruments of 



THE CONTROL OF COLOR 365 

this sort more suitable for general application and in which 
the light from a larger area is concentrated in order to 
provide sufficient light to analyze and measure with ease and 
precision. There is need also for an instrument which will 
more readily permit of analyzing color in terms of the re- 
agents used to create that color. Such an instrument also 
will be merely an improved adaptation of existing instru- 
ments and will be used in conjunction with a technique for 
working out quantitatively the combinations of pigments, 
dyes, or stains required to produce a given color effect. 

Auxiliary Instruments 

A number of devices are available in which the method 
of analysis consists in filtering through monochromatic 
filters. It should be observed, however, that such instru- 
ments do not analyze color in terms of hue, purity, and 
brightness as the eye sees color. They are, nevertheless, 
suited to certain applications in the arts, although they do 
not give the same complete range of measurement obtain- 
able by the use of the spectrophotometer. 

A useful instrument for many sorts of industrial purposes 
is known as the Hess-Ives Tint-Photometer. With this 
instrument it is possible to take readings of a subject as a 
percentage of the light reflected from a block of magnesia, 
and to compute the brightness therefrom. For bright flat 
colors, such an instrument yields a measurement of the 
color in terms of the primaries, red, green, and blue-violet, 
expressed as percentages of light taken through the same 
filters from the 100 per cent magnesia standard. 

Other filters are provided for special industrial uses. 
For the darker shades or mode colors the measurements 
would be less than 5 per cent and hence would be useless 
for practical purposes. For work of this sort, a neutral 
gray standard may be constructed for use instead of the 



366 THE CONTROL OF QUALITY 

magnesia block, care being taken to see that the new stand- 
ard is a true gray. It may be made by mixing lamp black 
with magnesia (carbonate or oxide). The use of a gray 
standard will throw the measurement well up into the scale. 
The author had used such standards which reflected less 
than 10 per cent of the magnesia standard and consequently 
multiplied the scale readings by 10 or more. The instru- 
ment may be used also for direct comparisons between a 
standard sample and the unknown subject. 

Reduction of Errors in Color Work 

Those who are interested in color work in industry would 
do well to make a close study of the phenomena involved 
from the physical standpoint, i.e., the study of color from the 
standpoint of light. Such a study should reveal the need 
of a more definite and precise terminology, the desirability 
of measurement in all its applications, and for the evolution 
of simple measuring apparatus, as well as of evolving appa- 
ratus more nearly suited to the needs of applied science. 

When instrumental means are not used, inspectors in 
color-matching should be checked by actual test, even if 
more exact methods are not available. In this manner, the 
dangers of large personal errors due to idiosyncrasies of 
color vision may be minimized. Everyone working with 
color should be warned against the errors due to contrast, 
and instructed in the relief of eye fatigue, caused by looking 
at brilliant red, for example, by such a simple expedient as 
an occasional glance at an equally brilliant green. The 
value of standardized matching lights would hardly seem 
to need mentioning. 

Such a study as that recommended will reveal industry's 
great need for the measurement of color in terms of figures. 
The possibilities for resulting economy in the arts are aston- 
ishing. 



THE CONTROL OF COLOR 367 

Standards of Appearance 

Needless to say the extension of the same precise con- 
trol scheme to other industrial problems besides color holds 
forth interesting opportunities for reducing errors and 
minimizing losses. It is not at all unlikely that a similar 
application of optical methods may be profitably developed 
to reduce various sorts of finishes, such as polished metal 
surfaces, to a basis of definite standardization. Optical 
instruments of other sorts have already been used exten- 
sively in a variety of industrial applications (e.g., the sugar 
and oil industries) and it is only reasonable to expect the 
adoption of such methods in other fields. 

Appearance, as previously indicated, is in reality nothing 
but light, but the qualities of this light which characterize 
a given appearance may be caused by a variety of things, 
such as the finish and texture of the surface, for example. 
That is to say, color is but one of the qualities which go to 
make up appearance; nevertheless, all of these qualities 
are subject to the same general treatment of analysis (both 
qualitative and quantitative), followed by the ascertain- 
ment of the relations between the final results and the 
causes thereof — in short, by the usual methods of science. 



CHAPTER XXII 

THE SCIENTIFIC ATTITUDE OF MIND 
AND ITS METHODS 

Science and the Arts 

It is usual for the people of the present day to observe 
with pride the progress made in the arts and sciences during 
the last century — a story of advances greater probably than 
in all previous time, and made at a rate that is still accelerat- 
ing. There are one or two aspects of this situation which 
are not so much of historical interest as they are of value in 
pointing the surest way to further and more rapid progress, 
especially in the manufacturing arts. 

The first of these thoughts is that the recent rapid im- 
provements in industry are dependent upon and followed 
after a great advance in the sciences. As Jevons says: 

A science teaches us to know, and an art to do, and all the more 
perfect sciences lead to the creation of corresponding useful arts. 
Astronomy is the foundation of the art of navigation. . . . 

The industrial arts have existed on a broad scale for 
ages, but in former times science shows only as a dim light, 
from time to time and in scattered places. Modern manu- 
facturing followed the wonderful scientific movement which 
began in force but a few generations ago ; it has progressed 
only so far as it has applied these scientific discoveries. 

The second and somewhat startling thought is that the 
arts, in large part at least, have whole-heartedly and strenu- 
ously resisted every attempt to introduce and apply the 
discoveries of science. Everyone is quite inured to the 
attitude of labor leaders in opposing the adoption of labor- 
saving devices, in spite of the fact that the greatest hope 

368 



THE SCIENTIFIC ATTITUDE OF MIND 369 

of the rank and file for a greater share of the good things of 
this world, lies in the production of more goods and better 
goods, with less effort. And the extra effort thus released 
is available to produce still other things which never ex- 
isted before. This attitude is an old story and a stupid 
one, but it is not entirely what is referred to here. For the 
source of much opposition to the adoption of improve- 
ments, or in fact of any conscious preplanned program for 
advancing industry, is to be found in the attitude of indus- 
trial executives, from foreman to manager to owner — es- 
pecially the latter, or scientific workers would be better paid. 

Science and the Practical Man 

In short, there exists the contradiction that industry 
owes its present high position to science, but industry 
habitually opposes further improvement. Industry, how- 
ever, will agree with one of science's principles, namely, 
that there must be a cause for every effect. That being so, 
there must be a cause for such a situation; which leads quite 
naturally to the conclusion that it ought to be worth the 
time and trouble to consider this matter rather carefully. 
Perhaps the inquiry may result in working out a compro- 
mise attitude of service to both parties. 

It must be admitted at once that conservatism is a useful 
thing, provided it is not reactionary. Sane opposition to 
change is doubly valuable. If men rushed to adopt every 
new device without careful consideration and practical 
test, we should all be living in the chaos of Sovietism, if we 
succeeded in holding ourselves even at that level. Further- 
more, opposition to change is necessary to secure the ad- 
vantage of the change. Newton said this in his third law 
of motion — "Action and reaction are equal and opposite." 
A force requires something to push against in order to 
build up its potential; and the opposition which must be 



370 THE CONTROL OF QUALITY 

overcome is the thing which develops real strength in any 
movement. Thus the measure of your belief in a principle 
depends upon and varies with your willingness to fight for 
it. With this realization, you will prepare yourself better 
to convince people that your plans are correct and to per- 
suade them that your ideas should be adopted. To do so, 
you must be thorough in your own preparation, which will 
result in having something better to sell than you had at 
first. In fact, a reasonable disagreement is encouraging 
because if everyone accepted what you said at once and 
without discussion, you would have nothing new or worth 
while after all. 

In the factory, however, one often encounters — perhaps 
I should say, one usually and very certainly encounters — 
something that is more than just conservatism. This at- 
titude is the particular hobby of the "practical" man, who 
takes genuine pride in being out of patience with all "the- 
ory." In the extreme form this type of factory executive 
recalls Lord Beaconsfield's definition of a practical man as 
one who practices the errors of his forefathers. 1 This at- 
titude of mind can be spotted at once, by recommending 
some slight improvement or change in method of carrying 
out a process. The "practical" man will assert that he has 
been doing it successfully as it is for the last twenty years 
(thirty-five is a favorite figure also) ; and will then talk 
about his experience. The best way to meet this attitude 
is by education — proving the point by teaching, step by 
step. It sometimes requires almost infinite patience to 
save such a man from himself. 

Theory or Theorists 

In all fairness, it must be said that there is a good deal of 
justification for the practical man's rejection of theory, and 

1 "An Introduction to Mathematics," by A. N. Whitehead (p. 40). 



THE SCIENTIFIC ATTITUDE OF MIND 371 

especially of theorists. The man who has the job of mak- 
ing things has to confine his interest to proved methods; 
his business does not provide time for speculation or ex- 
perimentation in working hours. When goods produced 
is the measure of achievement, as it must and should be in 
the shop, there is bound to be objection to even taking a 
chance of failure. Such losses should be confined to the 
laboratory, which should be kept separate from the shop for 
that reason. 

Too often also, the charge is true that the scientific 
worker is wholly out of touch with the practical details of 
the arts which should depend upon his work for their future 
progress. The scientist finds some measure of explanation, 
when this situation exists, both because his work is apathet- 
ically received by the practical man, as well as because he 
is professedly in search of knowledge for its own sake rather 
than for its immediate money value. ' ' There is a necessary 
unworldliness about a sincere scientific man; he is too pre- 
occupied with his research to plan and scheme how to 
make money out of it." 2 His greatest compensation lies 
in the realization, as Dr. George Sarton has so ably said, 3 
that man's intellectual advancement is the only real meas- 
ure of progress. Anything which helps to solve the ever- 
present problems which the world offers, means progress 
to the true man of science. If the solution is not useful 
now, it will be later on; and, if in the meantime he can carry 
on in his chosen field only at great personal sacrifice, then 
all the more reason to speak the truth at any personal cost 
and to worry little about the criticism or opposition of the 
moment. 

There is evidence on all sides of a lack of correlation of the 
sciences and the arts which doubtless is due to the difficulty an 



2 "The Outline of History," by H. G. Wells. 

3 See his essays in Scribner's on "The Message of Leonardo" and " Hidden History." 



372 THE CONTROL OF QUALITY 

individual encounters in adapting himself to these two viewpoints. 
For the benefit of his art, the artist should acquaint himself with the 
general sciences upon which his art is founded ; and for the benefit of 
progress the scientist should bear in mind the viewpoint of the artist. 
There should be no misapprehension regarding the relation of science 
and art, because the former supplies the enduring foundation of the 
latter. For this reason it appears that those who primarily possess 
a scientific viewpoint should attempt to bridge the gap by laying their 
course upon facts. 4 

The Engineer as Co-ordinator 

Granting that nothing but good can come from bridging 
the gap between science and industry, the only question to 
be answered is — "Who is the man to do it?" The engineer, 
either as executive or consultant, logically seems the man 
for the job. He either is or should be pretty close to both 
sides. If he is a real engineer he must be a fairly good 
scientist. If he is of any use in the manufacturing plant he 
must be practical in his viewpoint. As the friend of pro- 
duction, he will analyze its needs for science's help, and in 
the light of a sympathetic understanding bred of contact 
with the work. His observation, moreover, will be guided 
by a knowledge and appreciation of the methods of science, 
and his acquaintance with science will tell him where to 
look for further guidance. Once he knows the answer, his 
real task is to put it into form for practical use, and to make 
clear and convincing explanation of its fine points and ad- 
vantages to the man who must do the actual work. 

The engineer's purpose in industry should be to save 
effort by making it possible to do the job in hand more 
easily, and with a better product for a given effort. There 
are so many things to be done which have not even been 
started yet, that it is greatly to everyone's interest to free 
ourselves from just as much effort in doing our present work 

4 From the introduction to "The Language of Color," by M. Luckiesh, Director of Ap- 
plied Science, Nela Research Laboratories, National Lamp Works of the General Electric Co., 
Cleveland. 



THE SCIENTIFIC ATTITUDE OF MIND 373 

as we possibly can. To carry out this project in syste- 
matic form requires recognition of the fact that material 
progress rests upon an intellectual foundation; and, as we 
have seen, this in turn receives its greatest impetus from a 
peculiar mental attitude or method of thinking which is 
known as "scientific." Let us consider some of the special 
characteristics of this attitude. 

The Scientific Attitude 

Every small boy, unless he is most unlucky, passes 
through the stage of learning, rather early in his career, 
that he gains nothing by lying, crookedness, or not playing 
fair. Seemingly men have had to go through with much- 
the same process in their constant fight with nature. The 
world is a pretty decent place if we are careful to conform to 
nature's laws, but we are sure of defeat when we do not. 
The bridge that is designed to suit a present fancy, instead 
of being in strict conformity with the established laws of 
statics and the proved strength of its materials, is certain 
to fail. All engineering practice owes its rapid progress to 
the truthful observance of and strict adherence to known 
principles and proved facts. 

There are several ways in which such a body of knowl- 
edge can be secured, and when systematized into form for use 
it may be called "science." If this knowledge is obtained 
by the slow and expensive process of trial and error in 
actual practice, each success provides an indication of one 
limiting condition and each failure shows another limit; 
but the method can hardly be called scientific. That is the 
old method by which the arts used to advance. What 
special features distinguish the newer method ? 

One of the most obvious distinctions is that science is 
not satisfied merely to know that such and such a thing is 
true — it must know why. That the ultimate why is un- 



374 THE CONTROL OF QUALITY 

knowable merely adds zest to the game — it extends our 
horizon to the limits. Having discovered why, we are in 
a position to extend the application of the principle in- 
volved. Without knowing why, we could only repeat what 
had been done before. Thus the search for knowledge in 
the form of principles of general application is one of the 
chief characteristics of the scientific method. Its most 
obvious application in manufacturing is to know, in detail, 
the principles involved in the processes in use in the factory. 
Upon what elementary laws of nature do they depend, and 
what special adaptations of such laws are involved ? Look 
around you and see how many processes there are not, whose 
true inwardness is known. Many of the oldest will be 
found in this class. The latest, such as those peculiar to 
electrical work, have been able to profit by the discoveries 
of the science which made them possible. Even the proc- 
esses we think we know something about, still provide 
room for intensive study; which brings us to another char- 
acteristic of this special sort of mental attitude. 

The scientist approaches his problem with humility. 
Constant pondering over natural phenomena can have no 
other effect than to make clear the huge number and vast 
range of the knowable things which we still have to find 
out about. Against such a background, what we today 
call knowledge seems puny indeed. In this realization 
lies one of the scientist's greatest sources of power. Know- 
ing how little he knows, he makes very sure to see that his 
work is done with such precision that error is reduced to a 
minimum. He pays great attention to minute details, so 
that nothing shall be left out, because the answer may lie 
in some insignificant fact which is obscured by its very 
obviousness. Nothing is taken for granted, and although 
influenced by practical experience, he is careful to avoid its 
dangers by freeing his mind of traditional untruths. 



THE SCIENTIFIC ATTITUDE OF MIND 375 

The Scientific Method 

However humble the scientific man's attitude in pre- 
paring his mind to attack his problems, he nevertheless 
goes into action with confidence of success, because he has 
a method which works. Applied with determination and 
guided by good judgment, the scientific method is the one 
method that is certain to produce results sooner or later. 
For its guiding principle is fidelity to truth, and in this sense 
the achievements of scientific research are the greatest pos- 
sible vindication, in practical form, of the great moral law 
of honesty, in its broadest application. This is the first 
thought which should be driven home to every student of 
the engineering sciences. There is but one safe way to deal 
with natural phenomena, namely, to make sure, with pain- 
ful accuracy, that your facts are correct and complete, also 
that the conclusions drawn from these facts are sound in 
every particular. Then, if the principles and practices 
thus developed are translated into action with the same 
fidelity to truth, really useful results are sure to follow. 
The success of any other method is a matter of chance. 

In the effort to present in convincing form conclusions 
reached by the scientific method, the engineer would do well 
to take a leaf from the book of the lawyer, who must neces- 
sarily make very sure of the truth and completeness of his 
facts, and be certain that his deductions are both logical 
and precise. The literature on argumentation and the very 
practical methods for testing evidence and building briefs 
contain many useful hints which the engineer may adapt to 
his situation with profit. Not the least of these is the way 
in which the lawyer deals with the technical and scientific 
matters which arise within his purview. Realizing his own 
ignorance, he first makes sure to learn the story himself. 
Then he assumes an equal ignorance on the part of his 
readers and writes a clearer exposition and more convincing 



376 THE CONTROL OF QUALITY 

presentation of the technical matters involved than does 
the discoverer of these very phenomena. 

Then again, scientific work yields high returns for con- 
structive imagination. The latter is one of the rarest and 
least used of the mental processes, yet because of its for- 
ward-looking attitude it should be strongly developed. The 
mere statement that something is good enough as it is, or 
that further improvement is impossible, should be a sure 
sign to the engineer that right there is an opportunity. 
The situation may call for all his ingenuity, and surely for 
plenty of hard thinking. All the anticipatory and con- 
structive imagination he possesses may well be focused on 
the problem; but if this follows a thorough and truthful 
analysis of the problem in the first place, his hard work and 
late hours will be amply rewarded by results of practical 
value. 

The Place of the Engineer 

The reason for inviting attention to the preceding dis- 
cussion of the scientific attitude of mind and its methods, 
is to indicate the way in which we should go about the ad- 
vancement of the arts of manufacturing. The most suc- 
cessful method is obvious. It remains only to select the 
man to direct the job, because without a definite assign- 
ment and a systematic program we shall get nowhere. 
" Everybody's business is nobody's business." 

As already stated, the technically trained engineer is 
the logical co-ordinator of science and industry. Atten- 
tion is directed to the phrase "technically trained," because 
some men go through college without achieving that result, 
and others acquire education without going to college at all. 
But the man must be an engineer in the truest sense, regard- 
less of the route by which he has arrived at that specialized 
intellectual condition. 



CHAPTER XXIII 

THE METHOD OF ATTACK TO CONTROL 

QUALITY 

The Approach to the Problem 

There is a lesson for everyone contained in the Chinese 
philosophy which says that no theory has any value except 
in so far as it is translated into action or, at least, is trans- 
latable into action. Therefore if there is any merit in this 
theory of controlling quality, completeness requires that 
some plan be advanced for approaching the task of bringing 
quality under control. 

Since quality of output is the ultimate result of tech- 
nical processes in one form or another, it follows that the 
best way of solving problems in the control of quality is to 
use the scientific method. It is the best method for ob- 
taining rapid and certain returns. But it must be applied 
in a strictly practical engineering way because this is a com- 
mercial application of the method rather than a purely 
scientific search after knowledge for its own sake. The 
sort of knowledge wanted in this instance must be of im- 
mediate and economic use. 

Uniformity within Limits 

In crystallized form, the underlying object of any 
manufacturing enterprise is to make more and better goods 
for less money — to obtain a greater output of standard 
quality for less effort. In planning to bring quality under 
control, therefore, every step is made with a view to re- 
moving obstacles to greater and better output by regulating 
the deviations from standard. In every instance these 

377 



378 THE CONTROL OF QUALITY 

deviations or errors represent losses in the use of material, 
labor, and manufacturing plant. Perfect quality implies 
freedom from errors. But there is a limit to which quali- 
tative refinement can be carried with economy. Conse- 
quently, while it is true that we seek uniformity, it is a 
modified and reasonable degree of uniformity — that is, 
uniformity within commercial limits. The economy of 
manufacture requires that the limits be suitable for the 
case in hand at the moment — they must not be too large or 
too small. 

The scientific method is to be applied, then, to manu- 
facturing problems with quality as the criterion, but every 
solution worked out in this way must be mentally projected 
against a background of dollars and cents, and our conclu- 
sions modified accordingly to suit the present commercial 
situation. 

Getting the Facts 

In applying any such method to a given industrial situ- 
ation the first desideratum would appear to be an unbiased 
scrutiny of the business as it is. The art of seeing things as 
they really are is often a gift, but it can be cultivated also. 
The industrial executive is so close to the details of the 
business that the most obvious things escape him. Unless 
he recognizes this failing and stops to take stock of the 
situation he is very apt to get into a fix where "he can't see 
the woods for the trees." Yet an accurate viewing of the 
problem is prerequisite to any measure of success in laying 
out a program for constructive work. 

A prominent manufacturer who has a faculty for con- 
cise expression says that industry should heed the warning 
of his boyhood riding-master. The latter was in the habit 
of concluding his advice about sitting up straight and so on, 
by barking out — "Get off your horse and look at yourself 



THE METHOD OF ATTACK 379 

riding." Many a factory would be the better if its con- 
trolling executives would get off their horses and watch 
themselves riding — they wouldn't look so humped up to the 
disinterested outside observer. 

But after all, isn't this just another way of starting in to 
practice the things we have been considering in the last 
chapter? As we have just observed, one of the outstanding 
features of the scientific method is the collection of basic 
data, and the testing of such data to make sure that it is 
correct ; so that the first step is to get the facts in the case — 
starting with the general business situation and its trends as 
affecting quality, and then in all the detailed ramifications 
of the business itself. The first or general viewing has to 
do with external or commercial relationships, while the de- 
tailed study is for the most part a matter of regulating 
conditions within the factory. 

Analysis 

In securing the facts in detail it soon becomes evident 
that resort must be had to analysis. Manufacturing prob- 
lems are too large to be solved as a whole and must be 
broken up into parts which are small enough to suit the 
limitations of our intellectual equipment. Getting the 
facts is often the hardest part of the entire process, and the 
way in which the preliminary analysis is made becomes of 
great importance. 

Of course there is no exact and arbitrary scheme of 
analysis which can be rigorously applied to every case, but 
certain general guides should be followed, just as in the 
case of collecting and testing legal evidence. The first step 
is to make sure that we have all the facts and that they are 
facts — to test their truth. The next step is to exclude those 
which are clearly not pertinent to the problem in hand, as 
well as those which obviously are of such little influence as 



380 THE CONTROL OF QUALITY 

to be unworthy of consideration. Finally, the remaining 
data should be measured to determine the influence (and 
the relative influence) of each fact upon the problem as a 
whole. Thus measurement takes its place as a part of 
analysis, or more accurately, as a necessary accompani- 
ment to analysis. 

Tripartition or Tripartite Analysis 

Since there appears to be no generally accepted scheme 
for making sure that an analysis is complete and that all 
pertinent facts have been collected, I am venturing to sug- 
gest the use of a general guide or working rule which has 
proved of value in personal work. This working rule is that 
any complete analysis should be made from three principal 
viewpoints (or from at least three different angles). Its 
practical application works in this fashion — if you have 
examined a question from only one or two points of view, 
there probably is something missing; hence at least one 
more division of the subject should be made. On the other 
hand, in ordinary practice three main divisions of the sub- 
ject are enough. 

For example, it has been fashionable for labor and capi- 
tal to consider themselves as solely interested in so-called 
labor problems, whereas both sides to the controversy 
would have done well to consider the interests of the great 
third party — the public — which in this case holds the decid- 
ing vote. Another example more closely related to the 
work in hand is to be found in the common error of assum- 
ing that any cause has but one effect. The truth is that 
every cause has several effects. As a simple instance of 
this, suppose that a greater output is sought by the means 
of providing a high incentive in the form of a greatly in- 
creased piece rate. The cause (one element) is the higher 
incentive; the direct effect (the second element) is greater 



THE METHOD OF ATTACK 38 1 

output, but unless the accompanying additional effects 
(the third element) are considered and arranged for, the 
quality of the output will drop. Consequently, a complete 
analysis would provide at the start, with tripartition as a 
guide, for an adequate stiffening of the provisions for in- 
spection as a means of controlling quality to the desired 
standards. 

It may be mentioned incidentally and as a matter of 
interest that I adopted this tripartite guide in analytical 
work after observing the frequency with which careful 
thinkers divide their subjects into three main sections. A 
little consideration will show, however, that there is a basis 
for the method in the physical world all about us. Thus 
the three physical constants generally used as a foundation 
for measurement are mass, time, and space, each one of 
which (and many other physical things) again divides into 
three elements. 

The use of the three divisions of time (i.e., past, present, 
and future) will be found very useful in the analysis and 
subsequent solution of many factory problems. This 
time relationship as affecting the planning, production, and 
inspection groups in organization has been traced in Chapter 
V. It may often be utilized in the study of an individual 
process. For example, deviations from standard may be 
caused in the process itself; or they may be carried over 
from, or result from some cause in a previous process; or 
they may even be due to the influence of a subsequent 
process. All three possibilities should be considered. 
Thus, if the later processes are in need of work, the workers 
whose operation is in trouble may be unduly hurried; or 
they may be assuming that any errors they make will be 
corrected by subsequent and more precise operations. 
This third element (the possible influence of later opera- 
tions) is too frequently overlooked. 



382 THE CONTROL OF QUALITY 

The subject of color quality has been treated in Chap- 
ter XXI in accordance with the tripartite guide. 

Quality Records 

The basic data for analysis will be obtained from various 
sources. Such production and cost records as are at hand 
should be used as a starting point, but it generally will be 
found that the facts presented by such records are not 
sufficient nor are they arranged in the most useful form for 
the study of quality problems. As noted in Chapter VI, 
a well-organized inspection service is a very useful instru- 
mentality for the collection of facts relating to quality. 
But a preliminary analysis should be made and used as a 
basis for the quality records. 

Since quality involves uniformity within limits, the 
control of quality requires that quality records deal with 
variations from the working standards. They must show 
where and when these variations, or manufacturing errors, 
occur. This involves an analytical list of all the kinds of 
errors which do occur. They must show for each kind of 
error the relative frequency of its occurrence, and, in a 
general way at least, the size of the individual errors — all of 
which involves some form of measurement. 

Quality records, then, should present a list of character- 
istic qualities, a list of the kinds of error for each quality, a 
statement of the number and sizes of each kind of error, 
and a notation of when and where the error occurs. The 
cause of the error should be added if known, but, strictly 
speaking, the determination of causes is a matter for sub- 
sequent treatment. And all of the data is a subject for 
treatment by the methods of analysis and measurement. 
When the character of the quality prohibits a strict appli- 
cation of measurement for determining the relative size of 
errors, then the idea of measurement should be utilized by 



THE METHOD OF ATTACK 383 

comparison with standard samples graded in such a way as 
to provide limits. 

Using the Facts — Synthesis and Adjustment 

The scientific method, as we have seen, is not content 
to stop with a statement of facts — it must know why. In 
practical application this brings us to the determination of 
the causes of variations from standard. Once the reasons 
for the variations are known, we are a long way on the road 
to their correction. Again, it is a matter for analysis, for 
carefully thorough and logical reasoning, and for the use of 
constructive imagination in developing proper conclusions. 
For instance, errors which occur intermittently are prob- 
ably due to the way in which processes are applied. Pro- 
gressive increase in the size of an error probably indicates 
wear or change in equipment, and so on. 

Skill in this part of the work as well as in the selection 
of the most promising points of attack is something to be 
acquired solely by practice. No arbitrary rule applies and 
the solution in each instance will differ in details, although 
the methods used are alike in principle. 

After the problem has been analyzed and each small 
part treated separately, the separate parts must be put 
back together and adjusted. The procedure is analysis, 
synthesis, and adjustment (or compromise), as already dis- 
cussed in several places — notably in Chapter XVI, "Repe- 
tition Manufacturing." Thus the tolerance on a given 
dimension is a matter for agreement between engineering, 
production, and inspection. Correct and complete analysis 
is a very large part of solving the problem, because a de- 
tailed knowledge of the truth usually suggests the cure. 
Synthesis and its concomitant, adjustment, ordinarily re- 
quire a much shorter time to execute, but their vital im- 
portance cannot be too strongly stated — they call for all 



384 THE CONTROL OF QUALITY 

the available skill and good judgment which can be brought 
to bear upon them. 

The Order of Procedure 

When we come to the application of the method out- 
lined in the preceding, it is very evident that the approach 
from the standpoint of quality must begin with an intensive 
study of the product itself. This is the only sure and com- 
plete way of taking the true measure of an industrial situa- 
tion when quality is to be the primary guide. As suggested 
in Chapter II there should then follow a similarly careful 
study, first, of the processes used to create the product, 
then of the organization employed to apply these processes, 
and, finally, of the system used to measure the achieve- 
ments and control the operation of the organization. 

Admittedly the method of approach which starts with a 
searching analysis of the product and processes may be 
found to be somewhat arduous and exacting, but it soon 
becomes most interesting because of its great practical 
influence on the enterprise. Sometimes minute details are 
considered uninteresting, but as Gilbert K. Chesterton 
has remarked : "There is no such thing on earth as an unin- 
teresting subject; the only thing that can exist is an unin- 
terested person." 

Quality is a variable. Oftentimes the variations are 
small, but it is the amount of attention which is paid to 
just such little things that determines the difference between 
success and mediocrity. 

Begin with the Product 

Starting with the product, the first step is to analyze it 
as it is, and with reference to its characteristic qualities. 
In what respect should the individual articles making up the 
company's output be alike? The next step is to reduce 



THE METHOD OF ATTACK 385 

these characteristics to some basis of measurement for pur- 
poses of impersonal comparison. We can then determine 
to what degree of likeness it is sensible to make the indi- 
vidual pieces and establish tolerances and limits accordingly. 
This involves the determining of how far the articles may 
be unlike. At the same time, and by the same means, we 
may observe the direction which future improvement of the 
product should follow toward closer approximation to the 
ideal standard. 

Proceeding next to a study of the processes used in 
creating the product, the investigation takes the form of 
studying both processes and product together. The first 
object sought is a uniform product conforming with the 
predetermined working standards. This requires that the 
processes used to create the product must be controllable 
to an equal uniformity. To bring them to this condition 
we must proceed to list the various kinds of errors (or dif- 
ferences in the product), their magnitudes, and the fre- 
quency with which each kind of error occurs. The next 
step involves listing the possible and probable causes of 
these errors, as a step toward determining their actual 
causes. When the last-mentioned thing has been deter- 
mined, it is no very difficult problem in most cases to de- 
velop means and ways for reducing the errors — and often 
to eliminate them for all practical purposes. 

If the solution of the problem is not so easy to find, then 
we must turn back to pure science — the master teacher— 
and develop new methods from a fresh start. If your task 
seems too difficult, it will reassure you, perhaps, to take a 
look at the obstacles others have overcome. One trip 
through a plant making electric light bulbs, for example, 
is quite cheering. The winding of wire filaments too small 
for the eye to see the coils without the use of a microscope, 
and the actual use of the latter on production machines is 



3 86 



THE CONTROL OF QUALITY 




Figure 89. Precision Torsion Balance — Roller-Smith 



THE METHOD OF ATTACK 387 

typical ; as also is the weighing of these filaments to a pre- 
cision of 1 per cent for weights of less than 12 milligrams 
(see Figure 89), and this as a regular production proposi- 
tion. 

Written Descriptions of Processes 

Presently, as a result of this study, we shall know how to 
perform each process. As a matter of fact, in work where 
the product cannot be described by a plan (like heat treat- 
ing, or weaving, or making some chemical compound), the 
only method of description available is to build up an aggre- 
gation of explanatory descriptions, or written instructions 
for doing the work. Of course these process descriptions 
must be in complete detail, if they are to be of use either in 
analyzing matters affecting quality or for use in instructing 
workmen. The creation of such records involves learning 
your business in detail, but that is a knowledge the man- 
agement of any business should have if it intends to run the 
business, instead of letting the business run the manage- 
ment. 

There is one great distinction, however, that you can 
learn the technical details of the business by the scientific 
method, even though you are not actually able to do the 
work yourself — at any rate, you need not be able to do it 
as well as the man who is continually engaged in produc- 
tion. This is a bitter pill to the extreme type of "practi- 
cal" man. He is unwilling to disparage the results of 
years of devotion to his work — consequently he is quite 
likely to reject your advice for improvement by asking (of 
himself, at least), "How can anyone, who avowedly knows 
little if anything about this work, teach me how to do it 
better? Haven't I been working right at this same job for 
the last twenty-five years?" 

But, as doubtless you have already observed, this atti- 



388 THE CONTROL OF QUALITY 

tilde fails to distinguish between knowing the methods and 
principles used in doing the work, on the one hand (the 
why and how) and the skill required for their execution, 
on the other. One could write out the most particular 
instructions for shooting a rifle, but would only acquire 
the skill necessary for accurate shooting through continuous 
practice. Yet almost anyone could learn to shoot by follow- 
ing the written instructions exactly. 

It is a safe statement that man is not capable of doing 
anything which cannot be analyzed by the scientific method 
of attack and reduced to a description written in clear and 
simple language. Further, such a description may be used 
as the basis for improvement, once the governing principles 
have been worked out; and it can be employed as well to 
start any other intelligent person toward acquiring the skill 
needed in its execution. 

As a general rule, the oldest processes, which have not 
yet been subjected to such an investigation, are the most 
fertile field for its application. There is no mystery in any 
industrial process, although it may well be that great skill 
is required for its proper execution, and even the latter 
may be simplified. 

The Assemblage of Processes 

After the processes have been considered in detail, it is 
in logical order to consider them as merely the principal 
working parts of a great manufacturing machine — the 
factory as a whole. Shop arrangement (especially with a 
view to care of material in process) will show new values 
for system and order in physical form, as distinguished 
from mere paper systems. Consider the shop and inspec- 
tion arrangements with a view to planning with material 
and taking full advantage of the possibilities of the principle 
of centralized inspection. 



THE METHOD OF ATTACK 389 

Organization and System 

Taking up the organization next — is it well balanced as 
regards the main functions of planning, production, and 
inspection? For this much is fundamental in controlling 
quality. Is the factory personnel organized in a way to 
provide for bringing to the attention of the workmen, in 
effective form, the things they should know if quality is to 
be maintained as it is, and systematically improved there- 
after? Also, does the organization provide a competent 
person, whose duty is that of directing this improvement 
with the idea of making progress conscious and intentional ? 

Usually some form of committee system will be found 
useful as a means of educating the rank and file in the 
details of quality manufacture. It is well-nigh useless to 
spend money in bringing valuable facts to light, unless pro- 
vision is made for using them. Education is the first step 
toward accomplishing this, and to be effective, it should 
be reinforced by methods which make it clearly to the in- 
terest of the producer to put these lessons into practice. 

Finally, some economical sort of system, or systems, 
should be devised to present the statistics of the business 
(costs, qualities, and quantities) in clear and useful form 
for the guidance of the organization in correcting errors and 
eliminating wastes. The cost system especially should 
locate charges for damage and waste against the responsible 
department rather than against the department where they 
occur. 

In short, the whole process of controlling quality in- 
volves applying the scientific method to the industry, in a 
practical engineering way. Beginning with an untiring 
and systematic search for facts, we pass to a truthful, ac- 
curate, and sensible use of them in refining our work. The 
method is an invincible one for securing increased output, 
' at less expense of effort, and with higher quality. 



390 THE CONTROL OF QUALITY 

Conclusion 

Whether as a part of some general trend for which the 
times are opportune, or as the working out of economic 
laws, or as a combination of both (which is the most prob- 
able), business as a whole is working toward greater truth 
and fidelity to accuracy. This increasing tendency toward 
exact definition, which is the precursor of improved and 
better regulated quality, has shown itself rather promi- 
nently at times. Some years ago, for example, there began 
a great movement for "pure food." More recently, similar 
action has been taken for pure advertising, and one form of 
truthfulness which the latter has urged is the frank and 
open publication of technical details. Things are being 
called what they really are, and the proof supplied, instead 
of making mere assertions about quality and performance. 

This situation is encouraging, especially if you are one 
of those who believe that the business of the future will be 
built upon a sounder basis of merit, service, and worth, 
than ever before. If this is a correct viewpoint, then is 
not the control of quality the first step in that direction? 
Surely it is the basis for both service and the profit which 
follows real service. American industry has been famous 
for quantity production. Why should it not be distin- 
guished also for qualities that are definite and certain? 
When capitalists and industrial executives regard quality 
in this light, the biggest step toward the qualitative im- 
provement of industry will have been taken, because there 
is no serious difficulty in the way of its achievement. 

Very happily, quality is like many other things which 
you can have if you only want them badly enough. In his 
essay on "The Art of Seeing Things," John Burroughs says 
that the secret of the successful angler's effort is no doubt 
due to love of the sport. "What we love to do, that we do 
well." Without the strong desire for quality, beginning at 



THE METHOD OF ATTACK 39 1 

the very top of the organization, there is little chance for 
securing quality. Thus it is one of the prime responsibili- 
ties of ownership and management. 

There is no danger, either, in setting our ideal standards 
too high, because the fact that the realized standards are 
lower need not be discouraging. For it does not prevent 
the ideal from serving a most useful purpose, by indicating 
the direction improvement should take. "Ideals" — said 
Carl- Schurz — "are like stars. You cannot touch them 
with your hands but like the seafaring man on the desert of 
waters you choose them as your guides and, following 
them, you reach your destiny." 

Granted that quality is a desirable thing to have, the 
way to approach the task of placing it under sure control 
is the simple one of seeking true facts and being guided 
thereby, in accordance with a definite campaign. In the 
main, the methods most useful in the control of quality are 
merely the old-fashioned, time-honored ways of engineering 
with perhaps a little different slant. "Engineering is the 
art of organizing and directing men, and of controlling the 
forces and materials of nature for the benefit of the human 
race." There is nothing especially dramatic or mysterious 
about engineering methods, but the results of their intelli- 
gent and earnest application are pure magic. They present 
the most romantic possibilities for solving the problems of 
the world that confronts man in his upward climb. 



INDEX 



Accuracy, (See "Errors," "Measure- 
ment , " " Precision ' ' ) 
Adjustable limit gages, 307 

Illustrations, 222, 235, 307, 308 
Aisle arrangements, for central inspec- 
tion system, 132 
Chart, 133 
Alford, L. P., quoted, 14 
Allowance, 

denned, 254, 255 

precautions in working from, to 
determine tolerances, 255-258 
American amplifying gage, 298 
American International Corp., 

inspection form, 80 
American Locomotive Co., 

Illustrations, 18, 51, 96, 183, 192- 
196, 198, 199, 202 
quality control in war work, 188- 
202 

bullet manufacture, 197 
inspection, 201 

Illustrations, 51, 183 
shell manufacture, 188-197 

Illustrations, 192-196 
time fuse manufacture, 200 
Illustrations, 18, 198, 199 
Appearance, 

relation of color to, 347 
standards of, 367 
Armstrong Cork Co., 

experience with quality bonus, 21, 

23 
Assembling, 

department, inspection's aid to, 79- 
83 
example of selective assembly, 82 



Assembling — Continued, 

repetition manufacturing, economy 

in, 269 
standards, 261 
Automobile industry, 

example of highly developed form 
of inspection, 174-180 
at Packard Motor Car Co., 174- 
177 (See also "Packard Motor 
Car Co.") 
former practice, 178-180 
degree of precision, obtained in, 
331-333 

B 

Bench inspection, 164 
Bench inspectors, qualifications, 152 
Block gages, (See "Johansson block 
gages,"" Pratt & Whitney gages") 
Bonus, quality (See "Quality bonus") 
Brightness, a color constant, 355 
Brown and Sharpe Co., 
gages, 

Illustration, 305 
measuring machine, 287 

Illustration, 288 
micrometer calipers, proper method 
of using, 

Illustrations, 28, 31, 218, 253, 
257, 260 
Bulletin boards, suggestion for im- 
provements in, 90 
Bulletins, department, 158 
Bureau of Standards, 215, 216, 350 



Carnegie, Andrew, quoted in "Auto- 
biography," 17 



393 



394 



INDEX 



Central inspection, 49-52, 1 15-138 
advantages, 137, 138 
arrangement of shop, 123 

adaptation to high-grade close 

work, 131-134 
adaptation to rough work, 129- 

130 
line of flow of work first step in, 
123 

Chart, 123 
several spaces, 134 
at Lincoln Motor Co., 
at Packard Motor Car Co., 175 

Illustration, 37 
cribs (See "Central inspection 

cribs") 
forms of, 115 

self-counting trays, 1 16-122 

Illustrations, 118, 119, 120, 121 
two-bin system, 122 
most highly specialized form of 

inspection, 115 
standard, desirable, 135 
Central inspection cribs, 
Illustration, 126 
arrangement of material storage 
point in, 137 
Illustration, 137 
construction, 125 

Illustration, 127 
floor plan, 128, 129 

aisle arrangements, 132-134 
Charts, 128, 129, 132, 133, 135 
layout, 124 

Charts, 124, 125 
Charles-William Stores, inspection 

methods, 186 
Chief inspector, (See also " Inspection 
department, management of") 
bulletins issued by, 158 
location of office, 156 
organization of work, 144 

Chart, 145 
qualifications, 140-142 



Chief inspector — Continued, 
relation to organization, 

at Packard Motor Car Co., 174 

at Pratt and Whitney Co., 1 81 
staff, 

duties of, 1 48-1 5 1 

subordinates, 144 

understudies, 146 
titles, 143 

use of conferences, 157 
Church, A. Hamilton, quoted, 14 
Clearance, defined, 255 
Color, 346-367 

analysis of, methods, 359 

instruments, 361 (See also sub- 
heading "measuring instru- 
ments" below) 

monochromatic filters, 360 

prisms, 359 
appearance and, 347 
as light, factors of, 351-355 

eye, the, 355 

illuminant, the, 351-353 

subject, the, 354 
constants, 355 

brightness, 356 

hue, 355 

purity, 356 
control by standard samples, 348 

atlas of colors, 349 

color card, 213, 348-349 

dangers of, 350 
errors in work, reduction of, 366 
measurement of, 213 
measuring instruments, 361, 365 

monochromatic colorimeter, 363 

spectrophotometer, 362 

Diagram, 363 
tints and shades, 357 
tone, 355 
vision, 358 
Comparators, 298 
Hartness, 323 

Illustrations, 324, 325 



INDEX 



395 



Conditioning of material, standards, 

250 
Conferences, use of, by chief inspec- 
tor, 157 
Continuous processing, 

importance of uniformity in, 275 
Continuous product, 

practice in regard to inspection of 
manufacture of, 184 
Costs, 

decreased by, 

quality control, 15-19 
repetition manufacturing, 264- 
280 
selling, 24 

D 

Defects, remedy of, combined with 

inspection, 53 
Design, the, 237 
changes in, 

avoid if possible, 242, 245 
improvement, 243 
progress towards more exact, 240 
Dimension, (See also "Dimensional 
control laboratory," "Measure- 
ment") 
working standards, 252-254, 258- 
261 

basis of repetition work, 252 
definitions for, 254, 255 
Dimensional control laboratory, 281- 
302 
material equipment, 

Brown and Sharpe measuring 
machine, 287 
Illustration, 288 
comparators, 298 
Johansson block gages, 294-297 

Illustration, 297 
miscellaneous, 300 
Pratt and Whitney measuring 
machine, 289-293 
Illustrations, 290, 292 



Dimensional control laboratory — 

Continued, 

Pratt and Whitney precision 
gages, 298 

surface plate, 285 
physical conditions, 

cleanliness, 284 

floor coverings, 284 

furnishings, 285 

humidity, 284 

lighting, 284 

noise, 284 

temperature, 283 

vibration, 284 
Dispatching, relation of inspection 

to, 113 
Duplicate manufacturing, 277 

E 

Elgin National Watch Co., 

ratio of inspectors to workers, 182 
Employees, 

dimensional control laboratory, 
301 

discovering native ability among, 

153-155 

effect of inspection data on, 
reduction of fatigue, 93 
stimulus to interest, 90, 91 

inspection force (See "Inspection 
department, management of" 
and "organization of") 

number of, relation between out- 
put and, 162 
Engineering department, 64 

relation to inspection, 72 
Engineer, the, as co-ordinator of 

science and industry, 376 
Errors, 

in color work, 366 

in measuring, 232 
classes of, 227 
cure for, 231 



396 



INDEX 



Errors — Continued, 

frequency of occurrence, 228 

Chart, 228 
reasons for accumulation of, 226- 
232 
Eye, the, as a factor in color, 351 



Finish, 

effect on accuracy, 344 

standards, 251-252 
First-piece inspection, 59-61 
Fits, (See "Precision") 
Fixed-dimension limit gages, 304 
Floor-inspection, 52 

at Packard Motor Car Co., 175 

qualifications of inspectors, 152 
Flow of work in process, (See "Work 

in process") 
Foundries, practice in regard to 
inspection, 184 

G 

Gages, 303-316 (See also "Measuring 
instruments") 
adjustable limit, 307 

Illustrations, 222, 235, 307, 308 
application of, 311 
checking, 312, 313 

Illustration, 48, 282 
constitute working standards, 259 
fixed-dimension limit, 304 
fluid, 298 

Illustration, 167 
master, defined, 313 
micrometer calipers, proper method 
of using, 

Illustrations, 28, 31, 218, 253, 
257, 260 
multiplying, 309 

types, 310 
reference, defined, 313 
shop or working, defined, 313 
slip in transferring size, 314 



Gages — Continued, 
special, 310 
standard, defined, 313 
thread-gaging, (See "Thread-gag 

ing") 
tolerances, 311 

H 

Hartness comparator, 323 
Illustrations, 324, 325 
Hartness, James, quoted, 318-319 
Hoover, Herbert, quoted, 94 
Hue, a color constant, 355 



Illuminant, the, a factor in color, 351- 

353 
Industrial management, costs (See 
" Costs") 

employees (See "Employees") 

engineering department, 64 
relation to inspection, 72 

inspection, (See also "Inspection") 
purpose, help, 69 
recognition of importance of, 63 
relation of to engineering and 
production, 68 

inspection department, 67 (See also 
"Inspection department") 

organization parallel with govern- 
mental, 67 

planning (See "Planning") 

problems, advantages of quality 
control, 
costs decreased, 15-19, 24 
labor relationships improved, 

12-15 
output increased, 15-19 

production department, 66 
relation to inspection, 72 

quality a prime responsibility of, 

391 
real vs. apparent organization, 70 
Industrial revolution, the, 266 



INDEX 



397 



Inspection, 

American Locomotive Co., war- 
time work, 201 

amount necessary, 54-57 

automobile plants, example of 
highly developed form of, 173- 
180 

at Packard Motor Car Co., 174- 
177 

Chart, 174 
former practice, 178-180 

bench, 164 

central (See "Central inspection") 

continuous processing, 185 

continuous product, 184 

contribution of to general service, 

74-94 

arrangement, care, and analysis 

of work in process, 83 
collection of useful information, 

74 
handling rejected parts, 85-89 
in assembling department, 79- 

83 

provides production data, 89 

reduction of fatigue, 93 

stimulus to interest of individual 
workers, 90, 91 

trouble reports, 75-78 
Forms, 76, 80 
cost, relation between output and 

size of inspection force, 163 
cribs (See "Central inspection 

cribs") 
defined, 36 

relation to quality and quality 
control, 36 
department (See "Inspection de- 
partment") 
economies in, 61 
elimination of unnecessary, 57 
evolution of, 39 
extensive, when desirable, 173 

automobile factories, 174 



I nspection — Continued, 

machine tool manufacture, 181 
small precision work, 182 

first-piece, 59-61 

floor, 52 

at Packard Motor Car Co., 

175 

qualifications of inspectors, 152 
force (See "Inspection department, 

management of," and "organiza- 
tion of") 
foundries, 184 
gear, Lincoln Motor Co., 

Illustration, 88 
general machine shop, 184 
individual piece, final, Packard 

Motor Car Co., 175 
machine tool manufacture, 181 

relation of inspection department 
to organization, 181 
mail order houses, 186 
necessity for, 35-45 
operating, on finished vehicles at 

Packard Motor Car Co., 177 
relation to, 

engineering and production, 68 

planning, (See "Planning") 
rough stock, Packard Motor Car 

Co., 

Illustration, 58 
sampling, 59-61 
small precision work, 182 
tool and gage, Packard Motor Car 

Co., 

Illustration, 42 
types of, 46-53 

governed by special factory situa- 
tion, 46 

loosely organized, 184 

office, 47 

raw materials, 46 

tool, 49 

work in process, 49 (See also 
"Work in process, inspection") 



398 



INDEX 



Inspection department, (See also 

"Industrial management") 
importance of, recognition of by 

management, 63 
management of, 1 56-1 71 

bulletins, 158 

conferences, 157 

co-ordination of work, 156 

instruction of inspectors, 164-166 

female labor, 166-170 

location of chief inspector's 
office, 156 

morale, value of high, 170 

overtime, 162 

permanent personnel, desirability 

of, 159 
piece work, 161 
promotion of employees, 159 
proportion of output to size of 

force, 163 

Chart, 163 
task, 156 
wages of, 160 
working hours, 162 
organization of, 139-155 

basis, amount of work to be 

done, 142 
bench inspector, 152 
chief inspector, 140-142 (See 

also "Chief inspector") 
combination of line and staff, 

144 

Chart, 145 
development of, 139 
floor- inspectors, 152 
inspectors, 147-15 1 
personnel, discovering native 

ability among, 152-154 
personnel qualifications of, 151 
ratio of inspectors to workers 

(See "Ratio of inspectors to 

workers") 
related work, 142 
staff duties, 147-151 



Inspection department — Continued, 
understudies to chief inspector, 
146 
purpose, 69 
relation to organization, 

engineering and production de- 
partments, 64-69, 72 
in machine tool manufacture, 
181 
Inspectors (See "Chief inspector," 
"Inspection department, man- 
agement of" and "organization 
of") 
Instruments, measuring (See "Meas- 
uring instruments") 
Interchangeable manufacturing, 265, 
272 (See also " Repetition man- 
ufacturing") 



Johansson, C. E., 295 
Johansson block gages, 294 

Illustrations, 11, 222, 235, 239, 
241, 268, 273, 276, 297, 299 
remarkable accuracy of, 296 
secrecy of manufacture, 297 
Jones and Lamson Machine Co., 
Illustrations, 320, 324, 326 



Labor (See "Employees") 
Labor relationships, 

improved by quality control, 12-15 
Lassiter, C. K., quoted, 201 
Law of chance, 228 

Chart, 228 
Lewis, Huber B., quoted, 314-316 
Liberty motors, example of successful 

quality control, 203-206 
Light, color as (See "Color") 
Limits, 

defined, 254, 255 

precautions in determining from 
allowance, 255-258 



INDEX 



399 



Lincoln Motor Co., 

Illustrations, 37, 48, 71, 88, 204, 
205, 282 
central inspection in, 

Illustration, 37 
quality control in war work, 203-206 
Forms, 204, 205 
Luckiesch, M., quoted, 355, 371 

M 

Machine shops, general, 

practice in regard to inspection, 184 
Machine tool manufacture, 
by interchangeable manufacture, 

278 
example of highly developed form 
of inspection, 181 
relation of inspection department 
to organization, 181 
Mail order house, 

inspection methods at Charles- 
William Stores, 186 
Management (See "Industrial man- 
agement") 
Manufacturing, 

and art, difference, 264 
economies in (See "Repetition 

manufacturing") 
repetition, 264-280 (See also " Rep- 
etition manufacturing") 
schedule, basis of space assign- 
ments, 109 
Master control sheet, ior 
Master gage, defined, 313 
Material in process, 

necessity for continuous supply 

of, 99 
space assignments for, 1 1 1 
two-bin system of storage, 122 
Measurement, 210-232 (See also 
"Dimension," "Dimensional 
control laboratory") 
absolute accuracy impossible, 234 
defined, 234 



Measurement — Continued, 
errors in, 

accumulation of, 229-231 

classes of, 227 

cure for, 231 

frequency of occurrence, 228 

Chart, 228 
theory of, 226 
evolution of, 210-222 

comparison with graded scale, 

214 
instruments, 217-222 (See also 

"Measuring instruments") 
selection of qualities for, 211, 212 
standard samples, 212 
foundation of exact sciences, 210 
instruments (See "Measuring in- 
struments") 
precision in, 223-225 (See also 

"Precision") 
starting point of quality control, 

210 
units of, choice of, 217 
Measuring instruments (See also 
"Dimensional control labora- 
tory," "Gages," "Measuring 
machines") 
choice of, 222 
color, 361, 365 

monochromatic colorimeter, 363 
spectrophotometer, 362 
Diagram, 303 
comparators, 298, 323 

Illustrations, 324, 325 
danger of overgraduation, 220 
precision, 223-225 
requirements, 219 
Measuring machines, 
Brown and Sharpe, 287 

Illustration, 288 
Pratt and Whitney, 289 
Illustrations, 290, 292 
Mechanical devices, inspection by, 53 
Mechanical revolution, the, 267 



400 



INDEX 



Micrometer calipers, 
proper method of using, 

Illustrations, 28, 31, 218, 253, 
257, 260 
Monochromatic colorimeter, for 

measuring color, 363 
Monochromatic filters, use in ana- 
lyzing color, 350 
Multiplying gages, 309 
types, 310 

N 

North, Simeon, early exponent of 
interchangeable manufacturing, 
270 

O 

Office inspection, 47 

Operation data sheet, 104 
Form, 100-107 

Operation study sheet, 104 
Form, 105 

Operation symbols, 102-104 

Organization (See "Industrial man- 
agement") 

Output, increased by quality control, 

15-19 
Overgraduation of instruments, 

danger of, 220 
Overtime, inspection force, 162 



Packard Motor Car Co., 

Illustrations, 42, 58, 65, 167, 174, 
176, 179 
inspection, 

example of highly developed 

form of, 174 
organization, 174-177 

Chart, 174 
tool and gage, 
Illustration, 42 
Personnel (See "Employees") 
Piece work, 

in inspection department, 161 



Piece work — Continued, 

interfered with by uneven flow of 
work in process, 98 
Planning, 95-114 

dispatching, relation of inspection 

to, 113 
manufacturing schedule, 109 
master, 101 

master control sheet, 1 01 
materials in process, 

necessity for continuous supply, 

99 
space assignments, ill 

operation data sheet, 104 
Form, 106-107 

operation study sheet, 104 
Form, 105 

operation symbols, 102-104 

raw materials, necessity for con- 
tinuous supply, 98 

route tags, 108 
Form, 108 

work in process, 

allowance for losses in, 109 
determining quantities, no 
disadvantages of uneven flow, 

97. 98 
flow of, 95 
Planning department (See "Plan- 
ning") 
Polakov, W. N., quoted, 15 
Pratt and Whitney Co., 
gages, 

Illustrations, 150, 307, 308, 
315, 322, 323 
adjustable limit, 
precision, 298 
taper, 315 
thread, 
measuring machine, 289 
Illustrations, 290, 292 
relation of inspection department 
to organization, 181 



INDEX 



401 



Precision (See also "Dimensional 
control laboratory") 
advantages of, 281 
depends on service requirements, 

328 
dimensional, 330-345 

automobile experience, 331-333 
checks, quick, 345 
degree practicable, 330 
effect of finish on, 344 
obtaining, precautions in, 341 
tables of tolerances and limits, 
333-340 

Illustrations, 334-338 
gages, Pratt and Whitney, 298 
in manufacture of small high-grade 

articles, 182 
in measuring, 223, 224 
in workmanship, 225 
instruments, handling, 165 
torsion balance, 

Illustration, 386 
Prestometer or Prestwich fluid gage, 
298 

Illustration, 167 
Prism, use in analyzing color, 

Illustration, 359 
Product, 

study of, starting point of qual- 
ity control, (See "Quality con- 
trol") 
Production department, 66 
relation to inspection, 72 
Purity, a color constant, 356 
reducing, makes tints, 357 



Quality (See also "Quality control") 

a prime responsibility of manage- 
ment, 391 

defined, 4, 233-247 

essence of, 5 

incentive to increased production, 
91 



Quality — Continued, 

inspection the instrument for meas- 
uring (See "Inspection") 

records, 382 

standardization alone does not 
bring, 5 

standards (See "Standards") 

variability of, 235 

vs. quantity, 3, 19, 235 
Quality bonus, 20 

Armstrong Cork Co.'s experience, 

21, 23 

The Shelton Loom's experience, 
21 
Quality control (See also "Inspec- 
tion") 

advantages of, in management 
problems, 
costs decreased, 15-19 
labor relationships improved, 

12-15 
output increased, 15-19 
selling expense decreased, 24 

color (See "Color control") 

complexity of problem of, 187 

dimensional (See "Dimensional 
control laboratory") 

failure, instances of, 9 

measurement, relation of to, 210- 
232 (See also "Measurement") 

method of attack, 377-391 
analysis of facts, 379, 380 
beginning with the product, 384 
getting the facts, 378 
order of procedure, 384 
organization and system, 389 
quality records, 382 
study of processes, 385-388 
synthesis and adjustment, 383 

root of production economy, 279 

study of processes of making prod- 
uct, second step in, 385 
assemblage of, 388 
written descriptions of, 387 



402 



INDEX 



Quality control — Continued, 

study of product, starting point, 
25- 236, 384 
consumer requirements, 26 
design, 26-30, 236 
need of inspection, 33 
operating organization and rec- 
ords, 32 
processes, 31 
raw materials, 30 
workmanship, 32 
war time success in, examples of 
188-209 
American Locomotive Co., 188- 

202 
Lincoln Motor Co., 203-206 
Remington Arms Co., 206-208 
Quantity, 

vs. quality, 3, 19 

R 

Ratio of inspectors to workers, 186 
American Locomotive Co., 201 
General machine shops and found- 
ries, 184 
machine tool industry, 181 
Packard Motor Car Co., 177-178 
small precision work, 182 
Wahl Co., 141 

Raw material, 

importance of uniformity of, in 

repetition manufacturing, 273 
inspection, 46 
necessity for continuous supply of, 



Remington Arms Co., 

Forms and Illustrations, 105, 
108, 126, 246 
quality control in, 206-208 
Repetition manufacturing, 264-280 
basis of, establishment of working 

standards, 252 
economy in, 
assembling, 269 
labor, 267, 269 
development of, 

industrial revolution, 266 
mechanical revolution, 267 
duplicate manufacturing, 277 
interchangeable manufacture, one 

class of, 265, 271 
machine tool production, 278 
partial interchangeability, 277 
precautions in working from allow- 
ances to determination of toler- 
ances and limits, 255-258 
purpose, economy of production 
uniformity, 
at all stages essential, 265 
basis of, 264 

in continuous processing, 275 
in raw materials, 273 
work of Simeon North and Eli 
Whitney, 270 
Roller-Smith Co., precision torsion 
balance, 

Illustration, 386 
Route tags, 108 
Form, 108 



standards, 249 
Reference gage, defined, 313 
Rejected parts, 
handling of, 85-89 

at Packard Motor Car Co., 
176 

Form, 176 
percentage of, American Locomo- 
tive Co. war work, 201 



Samples, standard, 
color, 348 

atlas of, 349 

card, 348-349 

dangers of, 350 
selection of, in measurement, 212, 

213 

dangers in, 214 



INDEX 



403 



Sampling, in inspection, 59-61, 164 
Scientific attitude of mind, 368-376 
Self-counting trays, 

use in central inspection, 1 16-122 
Selling expense, 

decreased by quality control, 24 
Shell manufacture, 

American Locomotive Co., 188- 
197 
Shelton Looms, The 
Illustration, 185 
experience with quality bonus, 21 
Illustration, 22 
Shop arrangement (See "Central in- 
spection, arrangement of shop") 
Shop gage, defined, 313 
S. K. F. Ball Bearing Co., proportion 

of inspectors, 141 
Spectrophotometer, for analyzing 
color, 362 

Diagram, 363 
Spectrum, use in analyzing color, 

359 

Illustration, 359 
Springfield-Enfield Rifle production, 

quality control in, 206-208 
Stanbrough, D. G., quoted, 331-333 
Standard gage, defined, 313 
Standardization, 

quality not secured by alone, 5 
Standards, 

appearance, 367 
ideal, 233-247 

attainment of, difficult, 240 
defined, 239 

the design, 236-237, 239-247 
variations from, 235 
manufacturing, 236 
measuring, 

development of, 210 

for United States, 215, 216 

graded scale, comparison with, 

215 
samples, 212-214 



Standards — Continued, 

necessary in order to state a quality, 

233 
theoretical or 100 per cent, 237, 238 
uniform, 

basis of repetition manufacture, 

279 
securing, 7 
working, 

allowable variations from, 254, 

255 

assembling, 261 

conditioning of material, 250 

determination of, 248 

dimension and form, 252-254, 
258, 261 

finish, 251 

gages control, when used, 259 

precautions, 255-258 

raw material, 249-250 

tests, 262 
Surface plate, 

in dimensional control laboratory, 

285 
Swedish block gages (See "Johansson 

block gages") 
Sweet, John E., quoted, 238, 344 
Symbolization, 102-104 



Taylor, Dr. Frederick W., theory of, 

regarding inspection, 64 
Thompson, Gen. John T. , quoted, 207 
Thread-gaging, 

equipment, 326, 327 

Hartness comparator, 323 

Illustrations, 324, 325 
working gages, 322 
evolution of, 317 
interrelation of elements, 319 
precision depends on service re- 
quirements, 328 
purpose of, 318 
tolerances, 327 



404 



INDEX 



Time fuse manufacture, 
American Locomotive Co., 

Forms and Illustrations, 18, 
198, 199 
Tingley, Edward H., quoted, 1 17— 

122 
Tolerance, 

denned, 254, 255 

gages, 311 

precautions in determining from 

allowance, 255-258 
tables of, 333-34° 

Illustrations, 334-338 
thread gage, 327 
Tool inspection, 49 
Trouble reports, 75-78 

Forms, 76, 80 
Turnover, 

inspection department personnel, 

158 
Two-bin system of storage for mate- 
rial in process, 122 

U 

Units of measurement, choice of, 217 

W 
Wages, 

inspection force, 160 
piece work system, 161 
Wahl Co., proportion of inspectors, 
141 



War work, quality control in, (See 
"Quality control, war time suc- 
cess in") 
Wells, Frank O., quoted, 306, 327, 328 
Weston Electrical Instrument Co., 

inspection organization, 182 
Whitney, Eli, early exponent of inter- 
changeable manufacturing, 270 
Wolf, Robert B., quoted, 14 
Women as inspectors, 166-170 
Work in flow (See "Work in process") 
Work in process, 
analysis of, 85 
arrangement of, 83, 84 
determining quantities of, no 
flow of, 95 

Illustration, 96 
disadvantages of uneven, 97, 98 
line of, first step in arranging 
shop, 123 
Chart, 123 
inspection, 49 

by special mechanical devices, 53 

centralized, 49-52 

combined with remedy of defects, 

53 
floor, 52 
losses in, allowance for, 109 
Working hours inspection force, 162 
Working standards (See "Standards, 

working") 
Working or workman's gage, defined, 
313 



